The presidential race between Kamala Harris and Donald Trump is dominating the 2024 debate, but control of both chambers of Congress is also very much up for grabs — and a series of fluid races may produce surprises on election night, NBC News reports. These sleeper races could determine which party wins a majority in the House or Senate, which will have a substantial impact on the next president’s agenda. They will be decided by a mix of factors, including voter turnout and whether the candidates have a unique ability to defy the broader political winds. Here are nine races for Congress where one side should be clearly favored, but appears to have a battle on their hands. Texas Senate: Cruz fights to hang on Democrats need a miracle to maintain control of the Senate, and Texas may be their best chance to do so. Democratic Rep. Colin Allred is giving the polarizing Republican Sen. Ted Cruz a run for his money, presenting him as a do-nothing extremist. Cruz is casting Allred as too liberal for Texas by highlighting issues like transgender rights and energy production. The two-term incumbent is still favored in the GOP stronghold, though some surveys show his lead over Allred within the margin of error. Cruz has sounded the alarm, pleading with conservative donors to send him more money to fend off an onslaught from Allred and his Democratic allies. There’s added intrigue as Cruz underperformed in his last Senate race in 2018, fending off former Democratic Rep. Beto O’Rourke by less than 3 points. Nebraska Senate: Populist upstart spooks GOP This race was never supposed to be on the radar. But Dan Osborn — a 48-year-old mechanic, union leader and Navy veteran — has made a splash with his independent run as a populist outsider. Osborn substantially outraised two-term Republican Sen. Deb Fischer and launched buzzy ads vowing to upend the status quo. In one ad, he says the Senate is made up of “millionaires controlled by billionaires” and knocks Fischer as a career politician who is failing to deliver for Nebraska and only in Congress to enrich herself. High-quality statewide polls are rare, but available surveys show Osborn leading narrowly in some and Fischer ahead in others. Fischer remains favored in this ruby-red state, but what should have been a layup for her is now a real fight. Republicans have sent in the cavalry, pouring millions to tarnish Osborn as a left-wing Trojan horse who would strip away Senate control from the GOP. Osborn says he won’t caucus with either party if elected. Maryland Senate: Can Hogan defy gravity? Republican Larry Hogan won two races for governor of Maryland in 2014 and 2018, defying gravity in the deep-blue state. Now he’s trying his hand at a more challenging task: becoming the first Republican to win a Maryland Senate seat since 1980. Hogan is a heavy underdog in a state that Joe Biden won in 2020 by a whopping 33 points, where a focus on federal issues and growing party polarization make it tough for him. He is trying to ride the moderate image that served him well in his races for governor. His rival Angela Alsobrooks, a first-time federal candidate and the former Prince George’s County executive, is reminding voters about Hogan’s veto of abortion access legislation and highlighting the stakes for which party controls the Senate. Polls indicate that Hogan is dramatically overperforming Trump in Maryland, but still trails Alsobrooks. Florida Senate: Can Democrats oust Rick Scott? Florida is rapidly falling off the map for Democrats, and Trump is widely expected to carry it at the presidential level. But in the party’s search for an upset victory on a tough Senate map, some Democrats are holding out hope they can knock out Sen. Rick Scott, R-Fla. Scott, a former governor, has shown an uncanny ability to squeak out statewide wins by the slimmest of margins in Florida, including during the red waves of 2010 and 2014 and the blue wave of 2018. His rival, former Rep. Debbie Mucarsel-Powell, D-Fla., has largely focused on reproductive rights. Democrats hope some of Scott’s hard-right views will alienate moderates, and that a ballot measure to enshrine abortion access in the state constitution will help boost turnout on their side. Still, he remains the favorite. Pennsylvania’s 10th District: Former Freedom Caucus leader faces a serious threat This race has all the elements of a shocker in the works, with Rep. Scott Perry, a far-right incumbent in a moderately GOP-leaning district, facing the fight of his political career against Democrat Janelle Stelson, a former TV news anchor who is well known in the area. Stelson has crept up on Perry by raising eye-popping sums of money and portraying the former chair of the right-wing Freedom Caucus as out of touch with the district. Republicans are spending money to protect Perry, and he has responded by walking back some of his controversial positions, such as endorsing cuts to Social Security benefits. The Cook Political Report With Amy Walter recently redesignated this formerly GOP-leaning race as a “toss-up.” Virginia’s 2nd District: An early bellwether of how Republicans are holding up First-term Rep. Jen Kiggans, R-Va., is facing a challenge from Democrat Missy Cotter Smasal after a redrawn and more Republican-friendly district helped her knock off a Democratic incumbent by about 3 points in 2022. Virginia will be among the first states on the East Coast where polls will close the night of the election, so the results in this district will be viewed as a bellwether for whether Republicans are holding their ground in the types of districts they need to maintain the House majority. If Democrats flip it, it means they’re probably on their way to a good night. Wisconsin’s 3rd District: A controversial GOP freshman tries to hang on GOP Rep. Derrick Van Orden made plenty of headlines during his first two years in Washington, between hurling obscenities at Senate pages and heckling Biden during his State of the Union address. He’s favored in a red-leaning district previously held by centrist Democratic Rep. Ron Kind. But some Democrats see a tantalizing opportunity to persuade enough voters to split their tickets and deliver an upset. Democrat Rebecca Cooke is trying to do that by running as a moderate and an acceptable alternative in the district. Texas’ 34th District: A test of whether Latinos are drifting toward the GOP In a year of shifting coalitions, this heavily Latino district highlights a dynamic that could shape the 2024 election. Democratic Rep. Vicente Gonzalez is looking to hang on against Mayra Flores, a Mexican-born millennial who has promoted far-right rhetoric and is seeking to channel a resistance to transgender rights. Gonzalez is favored in this Democratic-friendly district, but surveys show Trump could make gains with Latino voters. The size of those gains, and whether the district has the appetite to be represented by a MAGA-aligned Latina, could potentially produce a shocker. California’s 47th District: Republicans eye an open seat in Newport Beach Two-term Rep. Katie Porter vacated this Orange County district to launch an unsuccessful run for Senate. The Republican candidate is Scott Baugh, a former California state legislator and Orange County GOP chair who lost to Porter by less than 4 points 2022. The Democrat is state Sen. Dave Min, who made headlines early in his bid by getting cited for misdemeanor drunk driving. California is emerging as a bright spot for House Democrats this cycle. If the GOP wants to dent their gains, this Newport Beach-area district — a onetime Republican stronghold that trended blue in the era of Trump — may be their best shot at flipping a district. This story first appeared on NBCNews.com.  More from NBC News: Five things to watch in the battle for Congress Trump doesn’t rule out banning vaccines if he wins Democrats think they can make inroads in rural Pennsylvania