The Democrats were able to hold on to their majority in the Senate because every incumbent secured reelection and Pennsylvania's lieutenant governor flipped the open seat.

The upper chamber of the Senate will shift from a 50-50 split to a 51-47 majority led by Majority Leader Chuck Schumer of New York in January. The lawmaker herself downplayed the idea that she would change her voting habits after she switched from the Democrats to the Independents.

The class of senators who were elected and reelected in the Democratic wave year of the year will face a difficult map in the years to come.

It is expected that President Joe Biden will run for reelection, which will affect the party's performance. Donald Trump's political brand took a huge hit last month after he endorsed multiple candidates who lost their races.

In four years, 34 senators will be up for reelection.

Both parties will likely target certain states.

Arizona

Democrats were reassured that her decision wouldn't affect the party's ability to control committee assignments and approve judicial nominations, even though she switched parties. Sinema hasn't said if she will run for reelection in 2024. She could end up in a three-way race with a Republican and a Democrat if she runs again.

Sinema's standing in the Senate would be complicated if Democrats decided to back her or not. The Democrats have made gains in Arizona in the last few years, and they want to keep the seat from being taken by the Republicans.

Debbie Stabenow
Sen. Debbie Stabenow of Michigan.
AP Photo/Jacquelyn Martin

Michigan

Stabenow was re-elected to her fourth term in the Senate by a 6.5% margin, which was her closest race since she was first elected to the Senate. Michigan Democrats had a banner year in November, sweeping the top statewide offices and retaking control of the full legislature, and Biden is expected to compete hard in the state if he runs for reelection.

Montana

Jon Tester is a political survivor having first won in conservative-leaning Montana in 2006 before winning tough reelection contests in 2012 and 2018? Republicans have been eyeing his seat for a long time, but he hasn't decided if he will run. Despite the GOP orientation of the state, Tester has been able to appeal to many of the state's Independents and Republicans.

Nevada

One of the most competitive battleground states in the country has a Democratic senator. The first-term congresswoman defeated the Republican senator by five points.

Nevada will be a top target for the eventual presidential nominees of the two major parties in the year 2024.

Sherrod Brown
Sen. Sherrod Brown of Ohio.
AP Photo/Mariam Zuhaib

Ohio

Despite the reddening of Ohio, which was once the nation's premier swing state, a strong populist connection has been maintained by the senator. Republicans will target this seat, but Brown has proven to be an effective candidate and one who has been able to win over Independents.

Pennsylvania

Since first being elected to the upper chamber in 2006 BobCasey Jr. has won all three of his Senate races with ease. In a presidential year where turnout in Philadelphia and Pittsburgh are likely to be very high, he'll have the advantage of running as a Democrat. Fetterman did well in many of the state's working-class towns and cities and could do the same in the election.

West Virginia

Manchin is the only Democrat who can hold the seat in a challenging state for his party. Manchin will need a lot of ticket-splitters to get another term in the nation's capital, since West Virginia was the second-best performing state in the 2020 election. Despite Republicans going all-out to defeat him, he won in the previous year.

Alex Mooney will be running for the seat.

Tammy Baldwin
Sen. Tammy Baldwin of Wisconsin.
AP Photo/Jacquelyn Martin

Wisconsin

Tammy Baldwin has not said whether she'll seek a third term in the upper chamber, but she has been able to win over many rural and exurban voters in her home state.

Baldwin has been able to navigate the divide in her state in a way that has been difficult for both parties.