The 10 Senate seats most likely to flip in 2018

Republicans are increasingly focused on the Senate as GOP donors and strategists grow more pessimistic about their ability to hold onto the House.

The prospect of a Democratic House has made Republicans desperate to take advantage of a favorable Senate map to hold or expand their majority in the upper chamber.

Republicans still have a strong chance of gaining seats, with 10 Democrats up in states President TrumpDonald John TrumpBiden, Sanders lead field in Iowa poll The Memo: Cohen fans flames around Trump Memo Comey used to brief Trump on dossier released: report MORE won in 2016. But while the GOP is mostly on the offensive, the party also faces the prospect of losing some seats.

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Here’s a look at the top 10 seats most likely to flip in 2018:


1. Sen. Dean HellerDean Arthur Heller How to reform the federal electric vehicle tax credit White House jumps into fight over energy subsidies One last fight for Sen. Orrin Hatch MORE (R-Nev.)

Heller is the only Republican incumbent defending a seat in a state Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonMemo Comey used to brief Trump on dossier released: report Trump will likely win reelection in 2020 Lanny Davis says Nixon had more respect for the Constitution than Trump MORE won in 2016 — bad news for him as Democratic enthusiasm surges. His opponent, Rep. Jacky RosenJacklyn (Jacky) Sheryl RosenSchumer walking tightrope with committee assignments 10 things we learned from the midterms Election Countdown: Florida fight ends with Scott, DeSantis wins | Dems see Sunbelt in play for 2020 | Trump to campaign in Mississippi ahead of runoff | GOP wipeout in Orange County | Ortiz Jones concedes in Texas House race MORE (D), has posted strong fundraising numbers and is trying to press Heller for his waffling on the GOP health-care repeal and his public role in crafting the GOP tax bill.

But Heller has recently seen a spate of good news that’s improved his chances of surviving in November. Primary challenger Danny Tarkanian dropped out of the race, allowing the senator to avoid making overtures to the GOP’s right flank that could hurt him in the general election. Republicans are also slowly cutting into Democrats’ voter registration advantage in Nevada.

2. Sen. Claire McCaskillClaire Conner McCaskillThe Year Ahead: Tech braces for new scrutiny from Washington McCaskill: 'Too many embarrassing uncles' in the Senate FEC votes to allow lawmakers to use campaign funds for personal cybersecurity MORE (D-Mo.)

McCaskill has always faced a tough road to reelection. She’s one of just three Democrats elected statewide in Missouri, which Trump won by almost 20 points. And the GOP is already seizing on McCaskill’s ardent support for Clinton in 2016 as a way to rile up the base.

Still, she’s won a reputation as a strong campaigner and a consistently prolific fundraiser this cycle.

State Attorney General Josh Hawley is still considered a top GOP recruit. But Republicans are closely watching his first-quarter fundraising haul following grumblings about his disappointing fundraising pace last year. The investigations into blackmail allegations against Missouri Gov. Eric Greitens (R) could add a tinge of scandal to the Republican brand in the state.

3. Sen. Joe DonnellyJoseph (Joe) Simon DonnellyHatch warns Senate 'in crisis' in farewell speech Dem senators Heitkamp, Donnelly urge bipartisanship in farewell speeches Schumer gets ready to go on the offensive MORE (D-Ind.)

The GOP primary between Rep. Luke MesserAllen (Luke) Lucas MesserHouse GOP to force members to give up leadership positions if running for higher office Indiana New Members 2019 Braun knocks off Donnelly in Indiana MORE, Rep. Todd RokitaTheodore (Todd) Edward RokitaIndiana New Members 2019 Braun knocks off Donnelly in Indiana How a bold new Disability Insurance proposal would benefit individuals with disabilities and taxpayers MORE and businessman Mike Braun remains one of the nastiest in the nation. The bruising primary fight will also draw down GOP cash reserves before the general election.

The ferocity of the primary gives Donnelly space to position himself as a bipartisan legislator, and he posted his best fundraising total of his career last quarter. But Donnelly will still have a rough go in Vice President Pence’s backyard. The Democrat’s fundraising still falls far short of the totals raised by many other Democratic incumbents, and his Republican challenger will have months to build his funds back up.

4. Arizona’s open seat (vacated by GOP Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeThe Hill's 12:30 Report – Cohen says Trump knew payments were wrong | GOP in turmoil over Trump shutdown threat | Kyl to resign from Senate at year's end Overnight Defense: Senate bucks Trump with Yemen war vote, resolution calling crown prince 'responsible' for Khashoggi killing | House briefing on Saudi Arabia fails to move needle | Inhofe casts doubt on Space Force Flake asks Daily Show where he can get a blanket emblazoned with his 'meaningless tweets' MORE)

Both parties think their leading candidates can win in Arizona. Reps. Martha McSallyMartha Elizabeth McSallyArizona governor eyes several possible Kyl replacements The Hill's 12:30 Report – Cohen says Trump knew payments were wrong | GOP in turmoil over Trump shutdown threat | Kyl to resign from Senate at year's end Jon Kyl to resign from Senate on Dec. 31 MORE (R) and Kyrsten Sinema (D) are strong fundraisers who know how to win tough fights. McSally is a veteran who can straddle the line between appealing to the right and to moderate voters, while Sinema is a Blue Dog Democrat with a compelling story who Democrats believe can compete statewide.

Sinema is a virtual lock for the Democratic nomination, but McSally has a rockier path in the GOP primary. She faces former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio — two controversial candidates who could steer the race to the right. Arizona’s August primary is held late in the cycle, giving the GOP nominee just 10 weeks to recover from a potentially rough primary.

5. Sen. Heidi HeitkampMary (Heidi) Kathryn HeitkampHatch warns Senate 'in crisis' in farewell speech Dem senators Heitkamp, Donnelly urge bipartisanship in farewell speeches House passes bipartisan bill aimed at reversing rising maternal mortality rates MORE (D-N.D.)

Republicans caught a break when they convinced Rep. Kevin CramerKevin John CramerDem senators Heitkamp, Donnelly urge bipartisanship in farewell speeches North Dakota New Members 2019 Rick Scott appears with GOP senators, ignores voter fraud question as recount continues MORE to mount a late bid against Heitkamp. Cramer has made his campaign about fierce loyalty to Trump, who won the state by 36 points in 2016. Cramer can also run on the statewide name recognition he’s built up as a three-term congressman in an at-large seat.

But Republicans had wavered on Cramer before, looking for other alternatives to the gaffe-prone congressman before ultimately settling on him as the top choice. And while Trump repeatedly pushed Cramer to run, the president has also been on good terms with Heitkamp, who has appeared on stage with him in North Dakota and flew on Air Force One.

The escalating trade war between Trump and China could also dampen the GOP’s prospects. China’s retaliatory tariffs threaten to hurt jobs in the agriculture-heavy state, an issue that could weigh on Cramer.

6. Sen. Bill NelsonClarence (Bill) William NelsonMcCaskill: 'Too many embarrassing uncles' in the Senate Bill Nelson uses farewell address to remind colleagues ‘no one person is above the law’ Coal supporter Manchin named top Dem on Senate Energy Committee MORE (D-Fla.)

Gov. Rick Scott’s (R) Monday entry into the race is a big win for Republicans, who previously faced long odds taking the swing-state seat. Scott will give Nelson the toughest race of his Senate career. The two-term governor has a formidable campaign operation, and his vast personal wealth will be an asset in Florida’s pricey media markets.

But this will also be a much different race for Scott. In the past, he’s only run in Republican wave years, winning by razor-thin margins even when the political atmosphere favored the GOP. And his closeness to Trump, who personally recruited him for the Senate race, could also be a potential drag in a state the president won by a little more than a point.

7. Sen. Joe ManchinJoseph (Joe) ManchinOvernight Defense: Senate bucks Trump with Yemen war vote, resolution calling crown prince 'responsible' for Khashoggi killing | House briefing on Saudi Arabia fails to move needle | Inhofe casts doubt on Space Force Hillicon Valley — Presented by AT&T — New momentum for privacy legislation | YouTube purges spam videos | Apple plans B Austin campus | Iranian hackers targeted Treasury officials | FEC to let lawmakers use campaign funds for cyber Manchin puts hold on FCC nomination over wireless internet fund delay MORE (D-W.Va.)

Manchin faces an uphill climb keeping his seat in a state that went for Trump by nearly 42 points. But Manchin could benefit from a brutal GOP primary fight.

The two-person race between Rep. Evan JenkinsEvan Hollin JenkinsWest Virginia New Members 2019 Republican Carol Miller holds off Democrat in West Virginia House race Trump to fundraise for 3 Republicans running for open seats: report MORE and state Attorney General Patrick Morrisey has been upended by a surge from former coal CEO Don Blankenship. Blankenship is polling well in the primary, even after serving a prison term over a fatal mine explosion. While Blankenship has the wealth to dominate the airwaves in the primary fight, Republicans fear he can’t win over more moderate voters in November.

Trump is going on the offensive against Manchin, after an initial show of bipartisanship with the senator. Flanked by Jenkins and Morrisey at a recent roundtable in West Virginia, Trump slammed Manchin for his vote against the tax overhaul.

8. Sen. Tammy BaldwinTammy Suzanne BaldwinDem senator accuses Wisconsin Republicans of 'power grab' Schumer reelected as Senate Democratic Leader Number of LGBT lawmakers in Congress hits double digits MORE (D-Wis.)

Wisconsin was once seen as a reach for Republicans. But the barrage of attack ads from outside GOP groups have softened Baldwin up ahead of November, prompting a flurry of Democratic spending meant to shore up the senator.

It’s still unclear who will emerge from the contentious GOP primary. Marine Corps veteran Kevin Nicholson, a former Democrat, is the pick of top conservative groups, but state Sen. Leah Vukmir has some big Wisconsin names in her corner.

9. Sen. Jon TesterJonathan (Jon) TesterSenate votes to overturn IRS guidance limiting donor disclosure Senate confirms Trump's pick to be deputy Treasury secretary O’Rourke is fireball, but not all Dems are sold MORE (D-Mont.)

Tester has built his campaign message around his willingness to work with Trump, a key argument in a state the president won by 20 points. And while the GOP hopefuls — state auditor Matt Rosendale, Judge Russ Fagg and businessman Troy Downing — are more focused on attacking Tester than blasting each other, the fluid primary still gives Tester some room.

Fortunately for Tester, Democrats aren’t extinct in Montana — Gov. Steve Bullock (D) cruised to reelection in 2016, even as Trump dominated.

Still, Tester has never won reelection with the majority of the vote, winning instead after a Libertarian candidate siphoned off votes from the GOP. This year, the presence of both a Green Party candidate and a Libertarian candidate on the ballot complicates that calculus.

10. Sen. Sherrod BrownSherrod Campbell BrownDem senator: Trump 'seems more rattled than usual' GOP rep: If Mueller had found collusion, ‘investigation would have wrapped up very quickly’ O’Rourke is fireball, but not all Dems are sold MORE (D-Ohio)

Judging only by its 2016 numbers, Ohio should be more competitive. The state is drifting right — Trump won by 8 points, and all of the top statewide officeholders are Republicans. Still, the GOP has struggled to dent Brown, and he’s pulled in impressive fundraising totals.

Republican front-runner Rep. Jim RenacciJames (Jim) B. RenacciGOP rep: If Mueller had found collusion, ‘investigation would have wrapped up very quickly’ House Ethics Committee extends probe into Renacci Sherrod Brown says he has 'no real timetable' for deciding on 2020 presidential run MORE has faced a spate of bad headlines in recent weeks about accusations that he failed to disclose political donations while registered as a lobbyist. He is looking to best businessman Mike Gibbons in the primary.

Other races to watch: Sen. Bob CaseyRobert (Bob) Patrick CaseyWould-be 2020 Dem candidates head for the exits O’Rourke, Brown shake up volatile Democratic horse race The Hill's Morning Report — Presented by T-Mobile — Democratic race for Speaker turns nasty MORE Jr. (D) still appears in the driver’s seat in Pennsylvania, even as GOP Rep. Lou BarlettaLouis (Lou) James BarlettaCasey secures third Senate term over Trump-backed Barletta Overnight Health Care — Presented by Purdue Pharma — Trump officials move to require drug prices in TV ads | 4,000 more people lose Medicaid in Arkansas | New top official for Medicaid Election Countdown: Cruz, O'Rourke fight at pivotal point | Ryan hitting the trail for vulnerable Republicans | Poll shows Biden leading Dem 2020 field | Arizona Senate debate tonight MORE steps up his fundraising. Former Tennessee Gov. Phil Bredesen (D) raised eyebrows by polling ahead of GOP Rep. Marsha BlackburnMarsha BlackburnOvernight Health Care — Sponsored by Amgen — ObamaCare signups lag behind last year despite recent surge | Drug company offers cheaper opioid overdose treatment after hiking price 600 percent | CDC calls fentanyl deadliest drug in US GOP struggles to win votes for Trump’s B wall demand Incoming GOP congressman says vaccines may cause autism, contradicting CDC MORE for the seat currently held by retiring Sen. Bob CorkerRobert (Bob) Phillips CorkerThe Hill's 12:30 Report – Cohen says Trump knew payments were wrong | GOP in turmoil over Trump shutdown threat | Kyl to resign from Senate at year's end The Hill's Morning Report — Trump maintains his innocence amid mounting controversies Overnight Defense: Senate bucks Trump with Yemen war vote, resolution calling crown prince 'responsible' for Khashoggi killing | House briefing on Saudi Arabia fails to move needle | Inhofe casts doubt on Space Force MORE (R), but she has time to boost her statewide name recognition. Mississippi’s special election is home to a four-way jungle primary that’s tough to handicap. And while Rep. Beto O’Rourke (R-Texas) is setting fundraising records, it’s unclear whether it’s enough to defeat Sen. Ted CruzRafael (Ted) Edward CruzBiden, Sanders lead field in Iowa poll The Memo: Cohen fans flames around Trump Biden team discussed 2020 run with O'Rourke as VP: report MORE (R-Texas).