rubio toomey
Sens. Marco Rubio, R-Fla., and Pat Toomey, R-Pa., are among the inclubents involved in races too close to call. Pictured: The two were captured as they walk to the Senate chamber, March 2, 2015. Joshua Roberts/Reuters

Democrats are hoping that with Donald Trump at the top of the Republican ticket, there’s a chance the U.S. Senate will swing back to Democratic control after Election Day.

Thirty-four Senate seats are up for election but only a handful of races are considered competitive and just seven are rated toss-ups by the Cook Political Report: Nevada, which currently is in Democratic hands, and Republican-held seats in Florida, Indiana, Missouri, New Hampshire, North Carolina and Pennsylvania.

Republicans hold 54 of the 100 U.S. Senate seats and Democrats hold 44 seats. The two independents in the Senate caucus with the Democrats. For the Democrats to regain control, they need to pick up a net five seats. Here are the races to watch:

harry reid
Sen. Harry Reid, D-Nev., is retiring from the Senate and selected state Attorney General Catherine Cortez Masto (right) to succeed him. Also pictured is Reid's wife, Landra, Aug. 4, 2016. Steve Marcus/Reuters

Nevada

Senate Minority Leader Harry Reid is retiring and picked state Attorney General Catherine Cortez Masto to replace him. She faces Republican Rep. Joe Heck, an emergency room doctor and brigadier general in the Army Reserve. The two candidates are wide apart on the issue of federal public lands with Heck arguing too much of Nevada (86 percent) is under federal control. Cortez Masto generally opposes handling public lands over to the state. She also sides with Reid on green energy, Mesquite Local News reported. The most recent Emerson College Polling Society survey gives Heck a 48 percent to 44 percent lead.

Florida

Sen. Marco Rubio is seeking re-election despite having said during his presidential bid he did not like the job. During the Republican presidential primary season, Rubio was pegged as among the senators with the worst attendance records. He squeaked by in the Florida primary to win his party’s nomination and faces Democrat Patrick Murphy. Murphy has painted Rubio, who has refused to pledge to serve out his term, as disinterested, wanting to use his Senate seat as a platform from which to gain the presidency, PoliticsUSA reported. The Emerson poll gives Rubio a 2-point advantage, 49 percent to 47 percent but Public Policy Polling survey puts the candidates even.

evan bayh
Former Indiana Gov. and Sen. Evan Bayh wants back into the Senate but his 26-point July lead has dwindled to just a few points. Pictured in 2010. Hyungwon Kang/Reuters

Indiana

Democrat Evan Bayh is trying to win back a place in the Senate, running against Republican Rep. Todd Young for the seat being vacated by incumbent Dan Coats. Bayh, 60, who also served as governor, was considered the favorite when he entered the race. Bayh left the Senate in 2011 to take a job with the U.S. Chamber of Commerce to lobby against excessive government regulation, but the chamber has been campaigning against him. Bayh’s campaign has run into trouble. Questions have been raised about his residency and parts of his private Senate schedule, the Indianapolis Star reported. The latest WISH-TV, Indianapolis, poll indicates Bayh’s 26-point lead in July had shrunk to 6 points by mid-October. Gravis, which has ties to the right-wing Breitbart organization, indicates Bayh’s lead is down to 2 points, 39 percent to 37 percent.

roy blunt
Sen. Roy Blunt, R-Mo., (second from left) is facing a challenge from Jason Kander, who famously put together an AR-15 blindfolded in a campaign ad. Pictured with Senate Majority Leader Mitch McConnell, R-Ky., May 17, 2016. Kevin Lamarque/Reuters

Missouri

Democrat Jason Kander is trying to unseat incumbent Sen. Roy Blunt, running on the premise nothing will change in Washington unless voters throw the bums out, echoing one of Trump’s talking points. That position has put Kander, 35, in position to pull off the upset, Roll Call reported. Kander is getting support from the Clinton campaign, which has been pouring money into the race. His campaign was highlighted by an ad in which he assembled an AR-15 blindfolded. The latest St. Louis Post-Dispatch poll shows Blunt has a 1-point lead, 47 percent to 46 percent, with 5 percent undecided.

Kelly Ayotte
Sen. Kelly Ayotte, R-N.H., tried to bolster her re-election efforts by repudiating her earlier support for GOP standard-bearer Donald Trump. Pictured: Oct. 12, 2015. Brian Snyder/Reuters

New Hampshire

Republican incumbent Kelly Ayotte faces Democrat Maggie Hassan, who regularly campaigns with Hillary Clinton and her surrogates. Ayotte, after months of supporting Trump, renounced her backing of the GOP standard-bearer and still maintains a lead over her rival even though Clinton is beating Trump in the state, the Concord Monitor reported. The Emerson poll gives Ayotte a 6-point lead over Hassan, 50 percent to 44 percent.

richard burr
The path to re-election for Sen. Richard Burr, R-N.C., is complicated by the presence of Donald Trump at the top of the Republican ticket as well as Gov. Pat McCrory's unpopularity. Jonathan Ernst/Reuters

North Carolina

Former Democratic state Rep. Deborah Ross is challenging incumbent Republican Sen. Richard Burr. Pizza delivery driver Sean Haugh, a Libertarian, also is in the race. Burr, chairman of the Senate Intelligence Committee, largely eschewed campaigning to focus on his Senate duties. His path to re-election, however, is being hampered by Trump’s campaign and unpopular Republican Gov. Pat McCrory’s re-election effort. In fact, Cook Political Report, has rated the state a toss-up for all three offices, Ballotpedia reported. The latest CBS/YouGov poll indicates Burr and Ross are tied at 44 percent apiece.

Pennsylvania

Trump’s lewd comments have thrown a spanner in GOP Sen. Pat Toomey’s re-election effort against Democrat Katie McGinty. Unlike most of his Republican counterparts, Toomey has signed on to gun-control efforts, co-opting a signature Democratic issue. There are nearly a million more Democratic voters registered in the state than Republicans, but Toomey predicts he will take many of them, USA Today reported. The latest Monmouth University poll indicates the candidates are tied at 46 percent apiece.