These 9 Senate races hold the key to who will control Joe Biden's agenda after the midterm elections in November

Incumbent: Mark Kelly, a Democrat

Primary date: August 2, 2022

Retired astronaut Mark Kelly will run for his first full Senate term this November after winning a special election in 2020. While the political landscape is challenging for Kelly, he's raking in lots of cash. He ended 2021 with more than $18 million in his campaign's coffers.

So far, nine Republicans are in the primary to take on Kelly this fall. The most serious candidates are Blake Masters, a chairman of the Thiel Foundation, which was created by billionaire investor Peter Theil; businessman Jim Lamon; and Arizona Attorney General Mark Brnovich.

While both of Arizona's US Senators are currently Democrats, the two seats were held for decades by Republicans. The current governor, Doug Ducey, is a Republican.

Arizona was one of the most hotly contested states in the 2020 presidential election. Joe Biden, a Democrat, won the state, but Donald Trump refused to accept the result, sowing widespread conspiracy theories among his supporters that unseen forces had somehow tampered with the vote. The disinformation campaign eventually resulted in a GOP-commissioned and highly criticized recount of Maricopa County's ballots, which reaffirmed Biden's win there. The episode has spurred Arizona Republicans to introduce dozens of bills in the state legislature aimed at protecting "election integrity."

Incumbent: Raphael Warnock, a Democrat

Primary date: May 24, 2022

Like Arizona, Georgia will be one of the most closely watched Senate races in the country due to its vulnerable incumbent, Raphael Warnock, and its significance for voting rights advocates.

Warnock, who is also a pastor of a church in Atlanta, won an upset victory against Republican Sen. Kelly Loeffler in a special election on January 5, 2021. Jon Ossoff, a second Democrat, also unseated Republican David Perdue in a runoff election that day. The dual victories handed Democrats narrow control of the Senate and gave the party a governing trifecta. It also changed Georgia politics forever.

Republicans would like one of their old seats back. As of early March, seven candidates have jumped into the Republican primary, but none have gained as much traction so far as Herschel Walker, a former NFL star turned Senate candidate who has won Trump's coveted endorsement.

But Walker, who has acknowledged past mental health struggles, has also faced allegations of domestic violence from at least two women, including his ex-wife, Cindy Grossman. The Georgia Senate race will test just how far a Trump endorsement will go, and whether it's powerful enough to overcome accusations like the ones facing Walker.

Incumbent: Marco Rubio, a Republican

Primary date: August 23, 2022

Thanks to Trump, Florida has become a political haven for Republicans, as the former president welcomes party members at his Mar-A-Lago resort in Palm Beach. Republican Gov. Ron DeSantis has also cast himself as a national opponent of coronavirus-related mask mandates, lockdowns, and social distancing requirements.

And yet Democrats are making a concerted effort to pick off one of Florida's two senate seats this year.

Republican Marco Rubio is running for his third term in the Senate, but he faces a challenge from several Democrats, most notably Rep. Val Demings, an Orlando-area congresswoman who was once floated as a potential vice presidential pick for Biden. Former Rep. Alan Grayson has also jumped into the Democratic primary.

A February poll released by the public opinion firm Mason-Dixon found that Rubio was leading Demings 49-42%, with 9% of voters undecided.

Incumbent: Catherine Cortez Masto, a Democrat

Primary date: June 14, 2022

Democrats are playing defense in Nevada, where Cortez Masto is running for her second Senate term. The former state attorney general is considered one of the four most vulnerable Democrats in the Senate, and Republicans are eager for the chance to regain ground in the Silver State.

Four Republicans have so far entered the race, but former Nevada attorney general Adam Laxalt has bolted to the front of the pack thanks to an endorsement from Trump. Laxalt, who is the grandson of former Nevada governor and senator Paul Laxalt, has cast himself in a Trumpian mold for the primary. However, he's not a guaranteed lock for the Republican nomination. Sam Brown, an Army veteran who was injured while deployed in Afghanistan, raised $2 million in 2021 and is gaining prominence in conservative media circles.

Incumbent: Maggie Hassan, a Democrat

Primary date: September 13, 2022

Republicans are eyeing the Granite State as one potential place where they could expand their Senate majority. But in late 2021, two of the GOP's most promising potential candidates decided not to run, leaving the party scrambling for a new candidate to unseat Hassan, a Democrat.

Gov. Chris Sununu, a Republican, reportedly considered a Senate run but decided not to enter the race, citing dysfunction in Congress. Former Sen. Kelly Ayotte, who Hassan narrowly defeated in 2016, quickly announced that she would not run, either.

With the Republican field devoid of a sure pick, other state officials are jumping into the race. So far, state Senate President Chuck Morse has declared his candidacy, as has former gubernatorial candidate Kevin Smith. Both lag significantly behind Hassan in terms of fundraising, but would likely get a boost from the national GOP apparatus should either win the primary.

Open seat

Primary date: May 17, 2022

With incumbent Sen. Richard Burr, a Republican, retiring, North Carolina provides an opening for both parties. Republicans are hoping to keep the seat in their hands, while Democrats see an opportunity to make gains in a state that Trump narrowly won in 2020.

On the Democratic side, Cheri Beasley, a former chief justice of the North Carolina Supreme Court, is seen as a frontrunner. Beasley made history in 2019 when Gov. Roy Cooper, a Democrat, appointed her chief justice. But she lost re-election to the post in 2021 to a Republican, Paul Newby.

Republicans, meanwhile, are assembling their own slate of candidates, but the race appears to be narrowing to a showdown between former Gov. Pat McCrory and current Rep. Ted Budd, who represents parts of Charlotte and Greensboro. Budd, who as a congressman supported objections to certifying the 2020 election results, won Trump's endorsement almost instantaneously.

Open seat

Primary date: May 17, 2022

Pennsylvania is gearing up to one of the most expensive showdowns of the 2022 primary season so far. Republican Sen. Pat Toomey's retirement has opened the door for a free-for-all primary season that's drawing in stars of both politics and popular culture.

On the Democratic side, Lt. Gov. John Fetterman currently leads the pack. However, he faces a serious challenge from Rep. Conor Lamb, who represents parts of suburban Pittsburgh and made national headlines for flipping a Trump-won district in 2018. State Rep. Malcolm Kenyatta, who would be Pennsylvania's first Black and openly gay senator if elected, has won endorsements from progressive entities like the Working Families Party, and the backing of numerous celebrities like director Lee Daniels, comedian Wanda Sykes, and feminist activist Gloria Steinem.

The Republican primary features a cast of characters that include none other than Mehmet Oz, the celebrity TV doctor who technically lives in New Jersey but has thrown his scrubs into the Pennsylvania Senate race.

The Republican field, which is about a dozen candidates strong, features notable supporters of Trump's bid to overturn and undermine the results of the 2022 Rep. Lou Barletta, who supported Trump as a so-called "alternate elector", has momentum in the race. State Sen. Doug Mastriano, who was outside the Capitol on January 6, 2021, was recently subpoenaed by a House committee investigating the insurrection but is running for Senate regardless.

Open seat

Primary date: May 3, 2022

Ohio will have an open Senate seat this year thanks to the retirement of Sen. Rob Portman, a Republican. So far, much of the oxygen is being sucked up by the Republican primary, which features several candidates who appear to be running to win over Trump as much as they are Ohio voters. The former president has not made an endorsement yet, but candidates are hopeful that a blessing from Trump could give them the edge in a chaotic field.

JD Vance, the author of "Hillbilly Elegy," has recast himself in a Trumpian mold, though he's struggled at times to convince voters of his loyalty to the former president. Instead, former Ohio state treasurer Josh Mandel seems to be winning the MAGA lane. Former Ohio Republican Party Chairwoman Jane Timken, state Sen. Matt Dolan, and investment banker Mike Gibbon are also running for the seat.

On the Democratic side, which is getting considerably less attention, Rep. Tim Ryan, who briefly ran for president in 2020, is the most nationally-known candidate. But also putting up a strong fight for the nomination are attorney Morgan Harper, a progressive who challenged Rep. Joyce Beatty to represent the Columbus area in 2020; and Traci Johnson, a longtime state employee who is now a tech executive.

Whoever wins the Democratic nomination will face off against one of the most conservative candidates of the 2022 cycle, and the race will likely become a referendum on how much power Trump still has to sway national politics to his liking.

Incumbent: Ron Johnson, a Republican

Primary date: August 9, 2022

Democrats are warily optimistic about Wisconsin, where Republican Sen. Ron Johnson will seek another term. Johnson has spread misinformation about COVID-19 vaccines by questioning their safety, despite the fact that the various vaccines available are deemed safe for nearly everyone to take. Johnson has also downplayed the violence perpetrated at the Capitol on January 6 by Trump's supporters, despite the fact that he was in the Senate that day and was evacuated by Capitol Police to protect him and his colleagues from the mob.

Democrats have reason for hope in a statewide election; Biden narrowly won Wisconsin in the 2020 election. And the state currently has a Democratic governor, Tony Evers, but Republicans control both houses of the state legislature. Regardless, several Democrats have jumped into the race.

The highest-profile Democratic Senate candidate so far is Lt. Gov. Mandela Barnes, who has raised about $2.3 million so far. Barnes has won endorsements from prominent Democrats like Sens. Elizabeth Warren of Massachusetts and Cory Booker of New Jersey, along with House Majority Whip Rep. James Clyburn of South Carolina. Sarah Godlewski, the Wisconsin state treasurer, is yet another high-profile politician running for the Democratic nomination