Republicans are on the cusp of winning the Senate majority after netting five seats overall and defeating two Democratic incumbents in Colorado and Arkansas.

The GOP needs to gain six seats to take the majority, and the party has pickup opportunities on the board in Iowa, Alaska and Virginia, where Sen. Mark WarnerMark Robert WarnerTop Democrat demands answers from CBP on security of biometric data 2020 Democrats raise alarm about China's intellectual property theft State probes of Google, Facebook to test century-old antitrust laws MORE (D) is narrowly ahead of Republican Ed Gillespie in a suprisingly tight race.

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Republicans have already picked up open seats in West Virginia, South Dakota and Montana, and they held on to a seat in Georgia, with David Perdue defeating surging Democrat Michelle Nunn without having to go to a January runoff. 

Vulnerable Kansas Sen. Pat RobertsCharles (Pat) Patrick RobertsHillicon Valley: Lawmakers ramp up Silicon Valley antitrust probe | Treasury sanctions North Korean cyber groups | Thiel to host Kobach fundraiser Ann Coulter, Peter Thiel slated to host fundraiser for Kobach's Senate bid: report Rep. Roger Marshall launches Kansas Senate bid MORE (R) also held on, beating back a vigorous challenge from Independent Greg Orman. 

Several late-closing states will prove crucial. Alaska Sen. Mark BegichMark Peter BegichAlaska political mess has legislators divided over meeting place Former GOP chairman Royce joins lobbying shop Lobbying world MORE (D) is seeking to hold off Republican Dan Sullivan, and it’s possible a close result in the sparsely populated state will lead to a recount or a very late call well into Wednesday. 

Arkansas Sen. Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D) was the first incumbent to fall on Tuesday. Freshman Rep. Tom CottonThomas (Tom) Bryant Cotton2020 Democrats raise alarm about China's intellectual property theft Bolton returns to political group after exiting administration Meadows, Cotton introduce bill to prevent district judges from blocking federal policy changes MORE (R) handily defeated the centrist lawmaker in a state that has slipped rapidly away from Democrats in recent years.

Colorado Rep. Cory GardnerCory Scott Gardner The 13 Republicans needed to pass gun-control legislation Bolton returns to political group after exiting administration The Hill's Morning Report — Trump's hurricane forecast controversy won't go away MORE (R) also knocked off Sen. Mark UdallMark Emery UdallPoll: Trump trails three Democrats by 10 points in Colorado The Hill's Morning Report — Trump and the new Israel-'squad' controversy Colorado candidates vying to take on Gardner warn Hickenlooper they won't back down MORE (D), defying Democratic cries that their vaunted ground game would save the vulnerable incumbent. 

Republicans also picked up a Democrat-held open seat in West Virginia with Rep. Shelley Moore CapitoShelley Wellons Moore CapitoThis week: House jump-starts effort to prevent shutdown Congress set to ignore Trump's wall request in stopgap measure America is in desperate need of infrastructure investment: Senate highway bill a step in the right direction MORE's (R) easy victory. 

South Dakota flipped to the GOP column after former Gov. Mike Rounds (R) won the open seat of retiring Democratic Sen. Tim JohnsonTimothy (Tim) Peter JohnsonTrump faces tough path to Fannie Mae, Freddie Mac overhaul Several hurt when truck runs into minimum wage protesters in Michigan Senate GOP rejects Trump’s call to go big on gun legislation MORE (D). The three-way race had become a late headache for the GOP with the addition of former GOP Sen. Larry Pressler (I), but with Republican attention and help the race turned again in its favor. 

Rep. Steve Daines (R) then won the open Democratic-held seat in Montana. 

With the early victories, Republicans are on the brink of their goal of Senate control. 

Sen. Mitch McConnellAddison (Mitch) Mitchell McConnellThe Hill's 12:30 Report: NY Times story sparks new firestorm over Kavanaugh Senator asked FBI to follow up on new information about Kavanaugh last year Congress must reinstate assault weapons ban MORE (R-Ky.) was declared the victor in his closely watched race as soon as polls closed in the Bluegrass State, defeating Democrat Alison Lundergan Grimes to earn a sixth term. Democrats had early hopes for the Kentucky secretary of State's candidacy, but her campaign couldn't take advantage of the senator's unpopularity in the state. 

McConnell might have to wait a bit longer to see whether he can add Senate majority leader to his title, however. 

A victor in the fight for the Senate majority may not be named until early Wednesday morning — or perhaps not even until December though. In Louisiana, there will be a runoff in December between Sen. Mary LandrieuMary Loretta LandrieuCongress needs to work to combat the poverty, abuse and neglect issues that children face Dems wrestle over how to vote on ‘Green New Deal’ Lobbying world MORE (D) and Rep. Bill Cassidy (R). Cassidy is seen to have an edge in the GOP-leaning state.  

There was good news for Democrats early on Tuesday too. Polls closed in North Carolina at 7:30 p.m., where Sen. Kay HaganKay Ruthven HaganTillis trails Democratic challenger by 7 points in North Carolina poll North Carolina businessman will challenge Tillis in GOP primary Embattled senators fill coffers ahead of 2020 MORE (D) was clinging to a narrow lead over Republican state Speaker Thom Tillis.

In New Hampshire, Sen. Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenOvernight Defense: Dems grill Trump Army, Air Force picks | House chair subpoenas Trump Afghanistan negotiator | Trump officials release military aid to Ukraine Defense spending bill advances over Democratic wall objections Democrats ramp up calls to investigate NOAA MORE (D) was able to hold the seat from challenger former Massachusetts Sen. Scott Brown (R), though the Republicans was refusing to concede late Tuesday as the race had tightened after the networks initially called the race for the incumbent. 

— Updated at 11:07 p.m.