The American people won’t just be selecting a president in November 2016. Along with House races, ballot initiatives and countless local offices, 34 United States Senate contests will appear on ballots around the country, with high stakes for both parties.

Republicans have built a majority in the upper chamber, but they face the daunting task this cycle of defending 24 GOP-held Senate seats, while Democrats are only playing defense on 10. Democrats need a net gain of either four or five seats to regain control of the upper chamber, depending on whether or not they also win the White House.

Here are six of the top races to watch one year out.

Nevada

If there’s one Democratic-held seat that Republicans are most eager to (finally!) capture, it may be Senate Minority Leader Harry’s Reid’s Senate seat. Reid eked out a reelection win five years ago after GOP nominee Sharron Angle imploded the party’s chances of taking down a top target.

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Now that Reid is retiring, Republicans have a solid recruit in Rep. Joe Heck, a physician and Army Reservist from a swing congressional district. Democrats also believe they have a top choice in former Attorney General Catherine Cortez Masto, whom Reid has already endorsed. It’s a race poised to go down to the wire, but some Republicans fear that Angle could give it another run, damaging their preferred candidate in the process.

Florida

If you need tales of animal sacrifice to keep you entertained about downballot races, never fear: Florida has you covered.

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With Florida Sen. Marco Rubio giving up his seat in his quest for the presidency, Florida voters are once again witnessing an unpredictable scramble for the seat in the swing state. On the Democratic side, Rep. Patrick Murphy made his run official back in March and won the backing of the political arm of Democrats in the Senate by May. But progressives, not happy with a former Republican as a standard-bearer, got their own candidate in famous liberal firebrand Alan Grayson.

The GOP field is even more crowded, with many conservative groups backing Rep. Ron DeSantis, with his House colleague David Jolly as well as Lt. Gov. Carlos Lopez-Cantera already in the race as well. (With the state’s late filing deadline, several others may throw their hat in the ring, too.) There are also some, well, unconventional folks in the race too.

A story about libertarian candidate Augustus Sol Invictus (not his given name) went predictably viral after an accusation that he sacrificed a goat to “the god of the wilderness” and drank its blood in the Mojave desert as part of a pagan ritual two years ago. And onetime Donald Trump adviser Roger Stone is in the race, too. Goat blood aside, the jumbled primaries on either side of the aisle promise an unpredictable race that will only be further complicated if a favorite son from the Sunshine State – Marco Rubio or Jeb Bush -- ends up on the presidential ticket, too.

Illinois

This Midwestern state hasn’t voted for a Republican president for more than 25 years, and its Republican incumbent is the most vulnerable senator on the ballot nationwide for 2016. Sen. Mark Kirk, a moderate who has endorsed gay marriage, is running his first campaign since suffering a stroke in 2012. He’s made his rehabilitation a big part of his campaign, with his first TV ad highlighting his determination to recover his ability to walk.

But while he has tried to appeal to more Democratic constituencies in the Land of Lincoln, he’s also been hurt by verbal missteps, including a statement that people drive faster through black communities. Democrat Rep. Tammy Duckworth, an Iraq War veteran who lost her legs and use of her right arm in a combat mission, is the DSCC’s favored candidate in the race. But she’s first facing a primary challenge from Andrea Zopp, an African American who once led the Chicago Urban League.

New Hampshire

As if New Hampshire isn’t already primed for the political spotlight with its all-important presidential primary in February, the suspense is almost sure to continue up until Election Day with a marquee Senate race between two well-known female lawmakers. The battle between Sen. Kelly Ayotte and top Democratic recruit Gov. Maggie Hassan promises to be perhaps the most competitive contest this cycle at the Senate level.

Early polls indicate that Ayotte, whose relatively moderate voting record in the Senate has helped to boost her stature in the Granite State, is running about even with Hassan, who was first elected governor in 2012. Both have strong approval ratings and are sure to highlight bipartisan work in a state known for politicians that don’t fit a partisan mold. A Democratic ticket featuring Hillary Clinton could be a boon for Hassan, who’s a top ally of the former secretary of state.

Wisconsin

In sports, as in politics, everyone loves a good rematch. The 2016 Wisconsin Senate race will pit incumbent Republican Ron Johnson against Democrat Russ Feingold, who lost his seat to Johnson during in the 2010 Republican sweep. Feingold is well known in the state from his previous 18-year tenure in the Senate – and he’s got some celebrity nationwide for his efforts to reform campaign finance laws.

Feingold has led in recent polls, and he’s likely to be helped by the fact that it’s a presidential year, but Johnson has been working to paint his foe as a career politician who has been plotting a comeback since being booted out of office. And the kind of vengeance that Feingold seeks is rare, too. According to the Rothenberg Gonzalez report, the last time that a defeated incumbent came back to win a later election was in 1934.

Ohio

In the quintessential battleground state, Democrats are hoping to pick off an incumbent Republican who easily won in a non-presidential year. Incumbent Rob Portman isn’t facing a strong primary challenge – despite GOP fears that he’d be targeted for his more moderate stances, including his support of gay marriage.

Former Governor Ted Strickland is vying for the seat on the Democratic side and has the backing of the DSCC, but he faces a primary challenge from 30 year-old Cincinnati councilman P.G. Sittenfeld, a favorite of progressives. Democrats note that Portman isn’t particularly well-known in the state, while Strickland’s four years as governor earned him a more robust name ID. Both sides are side to get plenty of attention from their respective presidential nominees, who will spend significant time in the swing state in the lead-up to 2016.