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 TrumpThe Hill's Morning Report - Sponsored by AdvaMed - House panel expected to approve impeachment articles Thursday Democrats worried by Jeremy Corbyn's UK rise amid anti-Semitism Warren, Buttigieg duke it out in sprint to 2020 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 HellerDemocrats spend big to put Senate in play This week: Barr back in hot seat over Mueller report Trump suggests Heller lost reelection bid because he was 'hostile' during 2016 presidential campaign MORE (R-Nev.)

Heller is the only Republican incumbent defending a seat in a state Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonDemocrats seek leverage for trial Davis: Trump vs. Clinton impeachments – the major differences Sharice Davids to vote for Trump impeachment articles: 'The facts are uncontested' MORE won in 2016 — bad news for him as Democratic enthusiasm surges. His opponent, Rep. Jacky RosenJacklyn (Jacky) Sheryl RosenSenate confirms Trump's 50th circuit judge, despite 'not qualified' rating Hillicon Valley: Facebook to remove mentions of potential whistleblower's name | House Dems demand FCC action over leak of location data | Dem presses regulators to secure health care data Senators introduce bill to create 'parity' among broadband programs 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 McCaskillGinsburg health scare raises prospect of election year Supreme Court battle MSNBC's McCaskill: Trump used 'his fat thumbs' to try to intimidate Yovanovitch GOP senator rips into Pelosi at Trump rally: 'It must suck to be that dumb' 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 DonnellyGinsburg health scare raises prospect of election year Supreme Court battle Watchdog accuses pro-Kavanaugh group of sending illegal robotexts in 2018 Lobbying world MORE (D-Ind.)

The GOP primary between Rep. Luke MesserAllen (Luke) Lucas MesserK Street giants scoop up coveted ex-lawmakers Yoder, Messer land on K Street House GOP to force members to give up leadership positions if running for higher office MORE, Rep. Todd RokitaTheodore (Todd) Edward RokitaLobbying world Female Dems see double standard in Klobuchar accusations House passes year-end tax package 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 FlakeLindsey Graham basks in the impeachment spotlight Kelly, McSally virtually tied in Arizona Senate race: poll The Hill's 12:30 Report — Presented by Nareit — White House cheers Republicans for storming impeachment hearing MORE)

Both parties think their leading candidates can win in Arizona. Reps. Martha McSallyMartha Elizabeth McSallyThe Hill's Morning Report - Sponsored by AdvaMed - House panel expected to approve impeachment articles Thursday Democrats spend big to put Senate in play Kelly leads McSally in Arizona Senate race: poll 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 HeitkampPro-trade group launches media buy as Trump and Democrats near deal on new NAFTA The Hill's Morning Report — Biden steadies in third debate as top tier remains the same Trump wins 60 percent approval in rural areas of key states MORE (D-N.D.)

Republicans caught a break when they convinced Rep. Kevin CramerKevin John CramerRepublicans consider skipping witnesses in Trump impeachment trial Senate braces for brawl on Trump impeachment rules GOP senator blocks Armenian genocide resolution 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 NelsonLobbying world Bottom Line Bottom Line 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) ManchinManchin warns he'll slow-walk government funding bill until he gets deal on miners legislation Krystal Ball: Is this how Bernie Sanders will break the establishment? Potential Dem defectors face pressure on impeachment 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 BaldwinIt's time for Congress to establish a national mental health crisis number The Hill's Morning Report - Presented by Better Medicare Alliance - Dems unveil impeachment measure; Vindman splits GOP The Hill's Morning Report - Presented by Better Medicare Alliance - Dems shift strategy on impeachment vote 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) TesterTrump trade deal likely to sow division in Democratic presidential field Krystal Ball: Is this how Bernie Sanders will break the establishment? GOP braces for Democratic spending onslaught in battle for Senate 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 BrownTrump trade deal likely to sow division in Democratic presidential field On The Money: Pelosi, Trump tout deal on new NAFTA | McConnell says no trade vote until impeachment trial wraps up | Lawmakers push spending deadline to Thursday Pelosi announces support for new Trump NAFTA deal 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. RenacciDemocrats fear Ohio slipping further away in 2020 Medicare for All won't deliver what Democrats promise GOP rep: If Mueller had found collusion, 'investigation would have wrapped up very quickly' 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 CaseyThe US needs to lead again on disability rights No one wins with pro-abortion litmus test New ObamaCare enrollment period faces Trump headwinds MORE Jr. (D) still appears in the driver’s seat in Pennsylvania, even as GOP Rep. Lou BarlettaLouis (Lou) James BarlettaEx-GOP congressman to lead group to protect Italian products from tariffs Head of Pennsylvania GOP resigns over alleged explicit texts Trump's most memorable insults and nicknames of 2018 MORE steps up his fundraising. Former Tennessee Gov. Phil Bredesen (D) raised eyebrows by polling ahead of GOP Rep. Marsha BlackburnMarsha BlackburnTikTok chief cancels Capitol Hill meetings, inflaming tensions Lawsuits pose new challenge for TikTok TikTok's leader to meet with lawmakers next week MORE for the seat currently held by retiring Sen. Bob CorkerRobert (Bob) Phillips CorkerRNC says ex-Trump ambassador nominee's efforts 'to link future contributions to an official action' were 'inappropriate' Lindsey Graham basks in the impeachment spotlight The Hill's 12:30 Report — Presented by Nareit — White House cheers Republicans for storming impeachment hearing 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 CruzOvernight Defense: House passes compromise defense bill | Turkey sanctions advance in Senate over Trump objections | Top general says military won't be 'raping, burning and pillaging' after Trump pardons Lies, damned lies and impeachable lies Conservatives rip FBI over IG report: 'scathing indictment' MORE (R-Texas).