Live election results: Who will control the Senate? Vox is tracking it here.

More than just the presidency is at stake tonight. The battle for which party will control the Senate is coming down to the wire, too — and could go either way.

Republicans hold a 54-seat majority in the Senate. Democrats need to pick up an additional four seats to regain majority control of the Senate if Clinton wins (five seats if Trump wins, because the vice president breaks Senate ties as the 51st vote).

We’ll be updating Vox’s Senate tracker here tonight as races are called, so be sure to look for updates as we track the balance of power in the Senate.

A quick guide to the eight competitive races we’re watching most closely

There are 34 Senate races this year, but only eight seem to have a decent chance of a seat switching from one party to another. There are four races where Democrats lead in the polls and four where Republicans are ahead. Most of them are very close at this point, with the exception of the Illinois race between incumbent Sen. Mark Kirk (R) and challenger Rep. Tammy Duckworth (D).

There are four races where Democrats are leading in the polls and stand the best chance of picking up seats

• Illinois, where Kirk is more than likely going to lose to Duckworth. Throughout the Illinois race, Duckworth has consistently led Kirk in the polls, but only in recent weeks has her lead broken double digits. She currently has a 13.3 spread over Kirk and is projected to win the race, easily giving Democrats one of four seats they need to pick up.
• Wisconsin, where incumbent Sen. Ron Johnson (R) is currently trailing behind challenger Sen. Russ Feingold (D). Aside from the Senate race in Illinois, which is strongly favored as a Democratic win, the Senate race in Wisconsin is the Democrats’ next best chance for a guaranteed victory. Feingold previously lost his seat to Johnson in 2010, but currently leads in the polls with a spread of 2.7 points.
• Pennsylvania, where Sen. Pat Toomey (R) is challenged by Katie McGinty (D), who served as an environmental adviser to Vice President Al Gore and President Bill Clinton. McGinty currently leads in the polls with a 2-point spread, but in the two most recent polls, Toomey had a 1-point lead in one of the polls and tied with McGinty in the other.
• Nevada, a Democratic open-seat contest where Rep. Joe Heck (R) is running against former state Attorney General Catherine Cortez Masto (D). Prior to the release of the 2005 tape where Trump bragged about sexual assault, Heck had led Cortez Masto in the polls, but after renouncing his support for Trump (which was met with boos), Cortez Masto has squeaked out a 1.8 spread, giving her a narrow lead.

There are four races where Republicans are leading in the polls — but in Indiana, by less than a point

• Indiana, a Republican open-seat contest where Rep. Todd Young (R) is up against former Sen. Evan Bayh (D). This is the most competitive race of the seven toss-ups, with only a 0.7-point spread separating Todd from Bayh. One poll put the spread at closer to 5 points in Young’s favor, but the RealClearPolitics average puts Bayh and Young within less than a point of each other.
• Missouri, where Sen. Roy Blunt (R) is being challenged by Missouri Secretary of State Jason Kander (D). Blunt currently leads Kander in the polls with a spread of 1.3 points, but as my colleague Andrew Prokop points out, there hasn’t been much public polling of the Missouri race, which means it has been hard to follow who might be ahead. The New York Times did report in October that both parties’ internal polling put Kander in the lead, but the presidential race has tightened since then, making it harder for Democrats to pull off an upset in this historically red state. One recent Emerson poll did give Kander a 1-point lead, however.
• New Hampshire, where Sen. Kelly Ayotte (R) is running against Gov. Maggie Hassan (D). Ayotte was heavily criticized for her support of Donald Trump and earlier this month made an amusing gaffe on whether Trump would be a good role model for children. Since then, she has renounced her support of Trump, but her lead in the polls against Hassan has tightened to only a 1.5-point lead.
• North Carolina, where Sen. Richard Burr (R) is facing a challenge from former state Rep. Deborah Ross (D). Burr has consistently led Ross in most recent polls, but his lead has narrowed to a 2-point spread. And one recent Quinnipiac poll put them at a tie.

There are 26 additional seats up for election — but the seats are unlikely to change parties

The rest of the Senate races likely won’t switch party this year. This includes 17 seats held by Republicans and nine held by Democrats.

This hasn’t always been the case: Up until a few weeks ago, Senate seats in Florida, Arizona, and Ohio were seen as pretty competitive races. But the races have opened up in recent days. In Florida, Sen. Marco Rubio (R) now has a 3.7-point lead over challenger Patrick Murphy (D). And in the other two states, incumbent Republicans John McCain and Rob Portman both enjoy double-digit leads over their opponents.

Meanwhile, only 10 Democratic seats are up for election. Plus, only one of the seats up for election is competitive (Nevada). Simply put, when it comes to numbers and odds, there are just a lot more Republican seats at stake in this election.

But how likely are Democrats to retake the Senate?

A Democratic-controlled Senate could be a game changer for a Clinton administration, breaking up some of the partisan blocs within Congress. What’s more, whichever party controls the Senate will have an enormous impact on determining who is appointed to the Supreme Court.

Since the 2014 midterm elections, Republicans have controlled both the House and Senate. They are expected to hold on to control of the House, as Democrats would need to pick up at least 30 seats to regain control.

But forecasters remain divided on just how likely Democrats are to retake the Senate. FiveThirtyEight gives Democrats a 50.7 percent shot (at one point it had predicted as much as a 70 percent chance), and the Upshot gives Democrats a 52 percent chance.

Meanwhile, both PredictWise and Daily Kos give Democrats as much as a 66 percent chance of winning, and the Princeton Election Consortium and HuffPost Pollster both heavily favor Democrats’ chances of winning the Senate. (Using 48 polls, the Princeton Election Consortium thinks Democrats have an 82 percent chance.)

That said, the one thing forecasters do seem to agree on is that if Democrats manage to retake the Senate, it’s going to be by a narrow margin of 50 or 51 seats. So a Democratic-controlled Senate likely won’t be a landslide victory by any means, but it will still be enough to dramatically alter the balance of power in Congress.

Source: http://www.vox.com/policy-and-politics/2016/11/8/13561514/live-election-results-tracker-senate