From Alaska to Maine, there are over a dozen competitive races on the map for control of the Senate, which has been in Republican hands since 2015.

Updates:
Joni Ernst fends off Democratic challenger Theresa Greenfield in Senate race
Ernst, an Army veteran, was first elected to the US Senate in 2014 as part of a GOP wave. She faced a much tougher race against Democratic nominee Greenfield to secure a second term.
Kelly Loeffler goes to a runoff for US Senate in Georgia
Loeffler, a Republican who was appointed to a US Senate seat in Georgia in late 2019 to replace Sen. Jonny Isakson, will advance to a January runoff against Democratic candidate Raphael Warnock in January to serve out the rest of Isakson’s term until 2022, Decision Desk HQ projects. 
Trump ally Lindsey Graham projected to hold on to Senate seat in deep-red South Carolina
Democrat Jaime Harrison put up a formidable fight in South Carolina, narrowly outpacing Graham in fundraising and tying polls leading up to the election. But as one of the most high-profile Republican Senators in the chamber, Graham managed to pull out the win in his historically Republican state.
Republican incumbent John Cornyn fends off close call from Democratic challenger MJ Hegar
Cornyn, who was first elected in 2002 and has served in a number of positions in Senate leadership, secured a fourth term in the US Senate by a narrow margin in a historically deep-red state.
Democratic Gov. John Hickenlooper defeated Republican Cory Gardner in Colorado
Hickenlooper, a former two-term governor and Denver mayor, unseated Gardner in Democrats’ first flip of a US Senate seat on election night. 
Senate Majority Leader Mitch McConnell defeated Democrat Amy McGrath in Kentucky
McConnell is one of the most high-profile politicians in the country and one of the most reviled among Democrats, helping McGrath raise an eye-popping $90 million for her campaign. Even despite McConnell’s unpopularity among Democrats and her own strong fundraising, McGrath was unable to topple the majority leader, who has held his Senate seat since 1986.
Control of the US Senate is on the ballot, with 35 Senate seats up for grabs across the country in 2020.
In-person voting locations have now closed in, Kentucky, South Carolina, and in most of Georgia, all of which are home to critical US Senate races 
Regaining control of the US Senate for the first time since 2015 is a top priority for Democrats, in addition to winning back the White House and maintaining their control of the House of Representatives.
Currently, the US Senate is made up of 53 Republicans, 45 Democrats, and two independents who caucus with Democrats, meaning that Democrats need to win back a net four seats to have a 51-seat majority.
Given that Democrats are likely to lose Sen. Doug Jones, in Alabama, they’ll need to pick up four seats to get to a 50-50 tie and a fifth seat for a majority. If Biden wins, Vice President Kamala Harris would also serve as president of the Senate and would be a tie-breaker vote.
Democrats’ most likely path to a majority is winning back seats in Colorado, Arizona, Maine, and North Carolina, and to pick up an additional seat in Georgia, Iowa, Montana, or Kansas to get to 51-49, according to election handicappers and forecasters.
Democrats taking back the Senate majority would be a significant achievement toward either delivering on Joe Biden’s ambitious policy goals, or blocking President Donald Trump’s second-term agenda.
For Republicans, controlling the chamber for the past five years has allowed the party to confirm hundreds of conservative judges, including many younger ones, to lifetime appointments on the federal judiciary.
Key Senate races 2020
Here are the US Senate seats most likely to flip parties, the top races that could shift control of the chamber:

• Alabama Senate: Democratic Sen. Doug Jones, who won a 2017 special election in a major upset, lost in his tough reelection fight against former college football coach Tommy Tuberville in Alabama.
• Alaska Senate: First-term Republican Sen. Dan Sullivan is facing a more competitive than expected reelection challenge from Al Gross, an Independent who would caucus with Democrats if elected.
• Arizona Senate special: Republican Martha McSally, who was appointed to the seat in late 2018, is running in a competitive special election against Democrat Mark Kelly, a former astronaut, and gun-violence-prevention advocate.
• Arkansas Senate: First-term Republican Sen. Tom Cotton is running for a second term without any Democratic opposition.
• Colorado Senate: Republican Cory Gardner lost his bid for a second term against former two-term Democratic Gov. John Hickenlooper. Colorado has trended from a purple state to a reliably Democratic one in recent years, making this seat one of the most likely to flip.
• Delaware Senate: Democrat Chris Coons defeated Republican challenger Lauren Witzke.
• Georgia Senate, regular: Republican David Perdue is seeking to defend his seat and earn a second term against Democrat Jon Ossoff, who is mounting a formidable campaign in a state trending toward Democrats.
• Georgia Senate, special: Republican Kelly Loeffler was appointed to replace Sen. Jonny Isakson, who retired in late 2019 because of health concerns. She ran in a jungle special election with candidates of all parties on the ballot and will face Democrat Raphael Warnock.
• Idaho Senate: Republican Sen. Jim Risch won a third term against Democratic challenger Paulette Jordan.
• Illinois Senate: Democrat Dick Durbin won a fifth term against Republican Mark Curran.
• Iowa Senate: First-term Republican Sen. Joni Erns won her competitive fight for a second term against Democrat Theresa Greenfield.
• Kansas Senate: Republican Rep. Roger Marshall defeated Democratic state Sen. Barbara Bollier for the open Kansas Senate seat vacated by retiring Sen. Pat Roberts.
• Kentucky Senate: Democrat Amy McGrath lost her bid to challenge Republican Senate Majority Leader Mitch McConnell in Kentucky, a race that attracted millions in outside spending but stayed in Republican hands.
• Louisiana Senate: First-term Republican Sen. Bill Cassidy won a second term against a bevy of challengers in both parties.
• Maine Senate: Longtime Republican Sen. Susan Collins is facing the toughest reelection fight of her nearly 24-year career in the US Senate against Democrat Sara Gideon, the speaker of the Maine House of Representatives.
• Massachusetts Senate: First-term Democratic Sen. Ed Markey won a second term against Republican Kevin O’Connor in a race that will likely remain in Democratic hands.
• Michigan Senate: First-term Democratic Sen. Gary Peters is running for a second term against Republican John James in a competitive race. Peters, along with Jones, is one of just two Democratic senators running for reelection in a state won by Trump in 2016.
• Mississippi Senate: First-term Republican Sen. Cindy Hyde-Smith is facing off against Mike Espy in a rematch of the 2018 special runoff election that she won by 7.2 points.
• Montana Senate: First-term Republican Steve Daines is facing a tough challenge for a second term from former Montana attorney general and two-term Democratic Gov. Steve Bullock.
• Nebraska Senate: First-term Republican Sen. Ben Sasse looks to defend his seat against Democratic challenger Chris Janicek.
• New Jersey Senate: Former Democratic presidential candidate and current Sen. Cory Booker won a third term against political newcomer Rik Mehta.
• North Carolina Senate: First-term Republican Sen. Thom Tillis is in one of the most competitive and expensive US Senate races in the country against former state Sen. Cal Cunningham.
• Oklahoma Senate: Longtime Republican Sen. Jim Inhofe defended his seat against Democrat Abby Broyles.
• Oregon Senate: Democratic Sen. Jeff Merkley won a third term in the Senate against Jo Rae Perkins.
• Rhode Island Senate: Longtime Democratic Sen. Jack Reed is defending his seat against challenger Allen Waters.
• South Carolina Senate: Republican Sen. Lindsey Graham won one of the most difficult reelection battles of his political career against fundraising juggernaut Democrat Jaime Harrison.
• South Dakota Senate: First-term Republican Sen. Mike Rounds won reelection against Democrat Dan Ahlers.
• Tennessee Senate: Republican Bill Hagerty defeated Democrat Marquita Bradshaw after incumbent Sen. Lamar Alexander did not run for reelection.
• Virginia Senate: Democratic Sen. Mark Warner won a third-term against Daniel Gade. 
• West Virginia Senate: Republican Shelley Moore-Capito won reelection against Democrat Paula Jean Swearengin. 
• Wyoming Senate: Republican Cynthia Lummis defeated Democrat Merav Ben-David for the seat held by GOP Sen. Mike Enzi, who is not running for reelection.