Senate Democrats have spent the past few months wrestling with President Biden’s social spending plan, voting rights legislation and the future of the filibuster. But now that 2022 has begun, they must now contend with the prospect of defending their exceedingly narrow majority in Congress’s upper chamber. Democrats control the bare minimum of 50 seats, along with Vice President Kamala Harris’s tie-breaking vote, meaning Republicans need a net gain of just one seat to take control.

But Democrats may actually have a better chance of retaining control of the Senate than they do the House, as the president’s party isn’t as susceptible to a midterm penalty in the Senate as it is in the House. That’s in part because only about one-third of the Senate is up each cycle, and the competitiveness of the seats up for election can vary a lot. To this point, Democrats could actually stand to benefit in 2022 because they don’t have to defend any seats in states former President Trump carried in 2020, while Republicans must protect two seats where Biden won — Pennsylvania and Wisconsin. 

However, thanks to how the electoral environment is shaping up and the low threshold Republicans need to surpass in order to regain a Senate majority, things are still looking pretty good for the GOP. In total, there are 34 seats up this November, but based on the median race rating from election handicappers at Inside Elections, Sabato’s Crystal Ball and The Cook Political Report, there are just nine seats at this point that aren’t classified as safe for one party. And it’s the seven seats in this category that are currently marked as toss-ups or leaning toward one party that will likely decide the fate of the Senate in 2022.

Let’s start with two of the most competitive Senate seats Democrats will have to defend in 2022: Arizona and Georgia. In 2020, these two Sun Belt states helped give Democrats their razor-thin majority, but now that region could hand Republicans control. Not only do two Democratic winners from last cycle have to defend seats they won in special elections — Sens. Mark Kelly of Arizona and Raphael Warnock of Georgia — but Sen. Catherine Cortez Masto of Nevada is also up in a state that Biden carried by only slightly more than 2 percentage points in 2020.

In Arizona, Kelly has built a massive campaign warchest of $18.5 million, but that’s no guarantee he’ll defeat whomever the GOP nominates in its competitive Aug. 2 primary. Republicans haven’t yet consolidated around a candidate, but there are three notables especially worth watching at this point: state Attorney General Mark Brnovich, Thiel Foundation president Blake Masters and solar energy executive Jim Lamon.

Brnovich could maybe be described as a bit of a front-runner, having led in a few early polls, but with support only in the high 20s his lead isn’t insurmountable, especially since he’s trying to walk a fine line of not angering Trump or the party’s base over his defense of Arizona’s 2020 election results. Meanwhile, Masters is backed by $10 million in super PAC money from tech billionaire Peter Thiel and is on the attack, blasting Brnovich for not sufficiently defending Trump’s false election claims, while Lamon has self-funded at least $5 million so far and has played to the base by running a digital ad in which he uses the euphemistic “Let’s Go Brandon” cheer to voice his disdain for Biden. Two other notable GOP candidates worth keeping an eye on are former Arizona National Guard head Mick McGuire and state Corporation Commissioner Justin Olson. It’s, of course, worth monitoring whether Gov. Doug Ducey jumps in, but that seems unlikely at this point, as he reiterated last week that he doesn’t plan to run for Senate.

The likely general election matchup is a bit clearer in Georgia, where Warnock will probably face Republican Herschel Walker, a hometown hero who won a national championship and the Heisman Trophy as the country’s best college football player at the University of Georgia in the early 1980s. Trump has already endorsed Walker and much of the GOP establishment has rallied to him, too, despite the fact he’s lived in Texas for many years. Walker has also been candid in the past about mental health issues, but there are a number of troubling episodes that could mire his Senate bid, including allegations of violence against women. 

Finally, in Nevada, Cortez Masto’s likeliest Republican opponent is probably former state Attorney General Adam Laxalt, who also has Trump’s backing after supporting Trump’s false election claims in 2020 as co-chair of the former president’s Nevada campaign. But Laxalt may not have smooth sailing in the June 14 primary thanks to Army veteran Sam Brown, whose moving story as a roadside bomb victim while serving in Afghanistan has attracted a lot of attention, as well as a couple million dollars in fundraising over the past two quarters.

It’s not just the Sun Belt that poses risks for Democrats, though. They may also struggle to defend Democratic Sen. Maggie Hassan’s seat in New Hampshire. Hassan did catch a break in November, when popular New Hampshire Gov. Chris Sununu announced he wouldn’t run against her. But while Hassan led many of her potential Republican opponents in recent general election polling, she’s not out of the woods because New Hampshire has one of the swingiest electorates in the country. Beyond New Hampshire, it’s not hard to imagine Colorado’s blue-leaning seat, held by Sen. Michael Bennet, also becoming competitive if things deteriorate further for Democrats.

Turning to Republican-held seats that will be competitive in 2022 and perhaps even provide pickup opportunities for Democrats, Pennsylvania and North Carolina, where Sens. Pat Toomey and Richard Burr are retiring, may be particularly close. Wisconsin, where embattled Sen. Ron Johnson is seeking a third term, is also likely to be competitive. Biden won Pennsylvania and Wisconsin while narrowly losing North Carolina, but such results may not be enough for Democrats this cycle because all three lean somewhat to the right, according to FiveThirtyEight’s partisan lean metric. That’s important because history suggests that it would be unusual for the GOP, as the opposition party, to lose seats that lean their way in a midterm. CNN’s Harry Enten recently noted that opposition-party incumbents in seats that leaned their party’s way (or away from the president’s party) had won 86 of 87 races in midterms since 1982. Pennsylvania and North Carolina are open-seat races, meaning there will be no GOP incumbent advantage, but even still, Enten found that the opposition party had won 32 of 35 such open seats.

Nevertheless, these races will be highly competitive — perhaps none more so than Pennsylvania, where both parties will have crowded primaries on May 17. The Republican race has been thrown wide open, too, with former Army Ranger and Trump-endorsed Sean Parnell dropping out amid scandal in November, creating openings for television personality and surgeon Mehmet Öz and hedge fund executive David McCormick to join a field that already included businessman Jeff Bartos, conservative commentator Kathy Barnette and former U.S. Ambassador Carla Sands. 

One of the key questions in the Republican primary moving forward, though, will be who Trump decides to endorse, and as such, many are trying to prove their Trump bonafides. McCormick’s background as an investor in China and his past comments criticizing Trump for helping drive polarization could be a problem for him, although he’s sought to inoculate himself against claims that he’s insufficiently “America First.” Still, Öz’s allies have worked to paint McCormick as China’s stooge, while Öz himself has played to anti-establishment sentiments by pushing his image as a “conservative outsider.” Sands, meanwhile, has tried to echo Trump’s nativist appeals by promising to fight “amnesty” for undocumented immigrants. No candidate has a particular fundraising edge either, given McCormick, Öz and Sands are all personally wealthy and can self-fund a substantial portion of their campaigns. That said, all three could be vulnerable to “carpetbagging” claims: Until recently, McCormick lived in Connecticut, Öz hailed from New Jersey and Sands was a California resident.

Meanwhile on the Democratic side of the Pennsylvania race, the four highest-profile candidates come in pairs from the state’s two major metropolitan areas — Pittsburgh and Philadelphia. At this point, Lt. Gov. John Fetterman, a progressive from the Pittsburgh area, looks to have the early edge in fundraising and in pretty much all public polling of the race. But Rep. Conor Lamb, who represents a district west of Pittsburgh, is hoping to come off as the most electable candidate with a more moderate profile and three House wins on competitive turf, while Montgomery County Commissioner Val Arkoosh and state Rep. Malcolm Kenyatta are hoping to leverage their connections to the far more vote-rich Philadelphia region. Arkoosh and Kenyatta aim to make history, too, with their bids. Arkoosh would be the state’s first woman senator, while Kenyatta would be the first Black person and openly gay individual to hold that office.

In Wisconsin, Johnson is running again, meaning all attention is on who Democrats will nominate, and right now, the early front-runner looks to be Lt. Gov. Mandela Barnes, a Black progressive who won his current office in 2018 and appears to have started this latest bid with a strong name recognition advantage. But Milwaukee Bucks executive Alex Lasry and state Treasurer Sarah Godlewski have also said they’re running and have until the Aug. 9 primary to eat into Barnes’s early lead. There’s also little question that Lasry will have ample financial resources, perhaps more than any other candidate, as he’s led the Democratic field in fundraising and is the son of the Bucks’ billionaire owner. But Godlewski has also put $1 million of her own wealth into the race and has an endorsement from EMILY’s List. Finally, Outagamie County Exec. Tom Nelson is also running, although he may find it difficult to gain traction with three better-funded contenders facing him.

In North Carolina, meanwhile, the Democratic primary has already been sorted out as state Sen. Jeff Jackson dropped out of the race in December and endorsed his rival, former state Supreme Court Chief Justice Cheri Beasley. But on the Republican side, former Gov. Pat McCrory and Rep. Ted Budd appear to be in a real knock-down, drag-out fight. McCrory led early on, but Budd’s polling numbers have improved over the past few months thanks to Trump’s endorsement and some $4 million from the conservative Club for Growth’s super PAC, which has committed $10 million to the race. Given Budd’s newfound advantage, he could also benefit from the state supreme court’s decision to delay the primary from Mar. 8 to May 17. (It’s possible, too, that it could be delayed even further to June 7 given litigation over redistricting.)

Beyond these three GOP-held seats, perhaps Florida and Ohio, and possibly Missouri, might get competitive, although Republicans currently have the upper hand in all three. In Florida, Republican Sen. Marco Rubio is likely to win reelection against Democratic Rep. Val Demings, thanks in large part to Florida’s GOP lean, although Demings, a Black woman who previously served as Orlando’s chief of police, may be about the strongest candidate Democrats could run. Meanwhile, crowded GOP primaries in Ohio and Missouri could nominate weak candidates and make those races more competitive — disgraced former Gov. Eric Greitens, who resigned in 2018 over a sexual abuse case, especially stands out in the Show Me State. But even then, Republicans could easily hold onto both seats, especially in a friendly electoral environment.

Missouri and Ohio are likely to remain in Republican hands, but they along with Alabama will have primary battles that could help shape the future of the GOP, while the race for an open Senate seat in deep blue Vermont could elect the first woman to ever represent the Green Mountain State in Congress. But that said, the battle for Senate control will likely rest on Sun Belt states like Arizona, Georgia, Nevada and North Carolina, as well as Frost Belt states like New Hampshire, Pennsylvania and Wisconsin.