Balance of Power: Could the Senate Majority Shift in the 119th Congress?

Democrats currently have a functional 51-49 majority in the Senate but are overwhelmingly on defense in this year’s election. The GOP could retake control of the chamber with a net gain of one or two seats, depending on the presidential results.

Current Senate balance of power for the 118^th Congress

To date, the current balance of power in the Senate is 51 (D) vs. 49 (R). The yellow dots are reflective of independents who are aligned with the Democrats.

The West Virginia seat of retiring Sen. Joe Manchin, a longtime Democrat who became an independent, is likely to fall to the Republicans. Democrats may need run the table in the other battleground contests just to keep 50 seats – a bare majority only if Democratic presidential nominee Kamala Harris also defeats former president Donald Trump for the White House, as the vice president breaks ties.

After West Virginia, the next-toughest seat for Democrats to hold is in Montana, where three-term Sen. Jon Tester is trying to fend off a serious takeover bid by former Navy SEAL Tim Sheehy (R) in a veteran-heavy state Trump carried by 16 points in 2020.

How many Senate seats are up for grabs in 2024?

Of the 34 Senate elections presently scheduled for 2024, Democrats and allied independents are the defending party in 23 contests, including high-profile races in such battleground states as Arizona, Ohio, Michigan, and Pennsylvania.

Eleven Republican-held seats are up for grabs. Nebraska will have two races, including a special election triggered by the resignation of Rep. Ben Sasse (R).

In the 2024 U.S. Senate election, 34 seats are up for grabs, including 11 Republican-held seats and 23 spots held by Democrats or allied independents.

Open Senate races in 2024

Nine incumbent senators are not seeking reelection in 2024: five Democrats, two Republicans, and two Independents:

• AZ: Krysten Sinema (I)
• CA: Laphonza Butler (D)
• DE: Tom Carper (D)
• IN: Mike Braun (R)
• MD: Ben Cardin (D)
• MI: Debbie Stabenow (D)
• NJ: George Helmy (D)
• UT: Mitt Romney (R)
• WV: Joe Manchin (I)

What are the competitive Senate races to watch in 2024?

Of the 34 Senate races this year, eight seats are considered competitive as of Oct. 8, 2024, according to the Cook Report with Amy Walter.

The three most competitive races are toss-ups that either the Republican or Democratic candidate have a fair shot at winning:

• Michigan: Former Rep. Mike Rogers (R) and Rep. Elissa Slotkin (D) are going head-to-head to fill Sen. Debbie Stabenow’s (D) seat as she prepares to retire.
• Ohio: Incumbent Sherrod Brown (D) is the only statewide elected Democrat in a former swing state that has since shifted to the GOP. He faces challenger Bernie Moreno (R), a Trump-backed businessman.
• Wisconsin: Incumbent Sen. Tammy Baldwin (D) is seeking a third term in the swing state. She faces GOP nominee Eric Hovde (R), a wealthy investor who ran for Senate in 2012.

Five other states have tough Senate races, where one party has a slight edge over the other.

Republicans have an advantage in:

• Montana: Senate Veterans’ Affairs Committee Chair Jon Tester (D) is running for a fourth term in a pro-Trump state. Tester faces Tim Sheehy, a businessman and ex-Navy SEAL, who easily won the Republican nomination after gaining backing from National Republican Senatorial Committee Chair Steve Danies. Montana moved to “lean Republican” from tossup on September 12, increasing the odds of a GOP flip in the upper chamber.
• Texas: Two-term Sen. Ted Cruz (R) is being challenged by Rep. Colin Allred (D) in a race that has tightened in recent months; Cook Political Report has moved it from “likely Republican” to the more competitive “lean” category.

Democrats, on the other hand, have an edge over their GOP opponents in:

• Arizona: Although she lost the 2022 gubernatorial election, Kari Lake (R) won the 2024 Republican nomination for Senate with 55% of the primary vote. Rep. Ruben Gallego (D) won the Democratic nomination unopposed. Incumbent Sen. Kyrsten Sinema, a Democrat turned independent, is not running for reelection.
• Nevada: Incumbent Sen. Jacky Rosen (D) is seeking a second term against the establishment-preferred Army veteran Sam Brown (R). In 2022, Nevada had the closet Senate race in the country when Sen. Catherine Cortez Masto (D) edged out Adam Laxalt (R) by 0.8%.
• Pennsylvania: Incumbent Sen. Bob Casey (D) faces the former Bridgewater Associates CEO Dave McCormick (R). If Casey is reelected, he’ll be the first Democrat to win a fourth Senate term in Pennsylvania.

Which current elected officials are likely to be elected to the Senate?

Five House members and a governor are favored to win their 2024 Senate races:

• Jim Banks (R-IN): The Indiana congressman has backing from party leaders after sitting Sen. Mike Braun (R) opted to run for governor.
• Lisa Blunt Rochester (D-DE): The Delaware congresswoman easily won her primary to replace retiring Sen. Tom Carper (D). If elected, she’ll be the state’s first Black female senator.
• Jim Justice (R-WV): The two-term West Virginia governor is set to succeed Democrat-turned-independent Sen. Joe Manchin, whose retirement nearly guaranteed that the seat would flip to red.
• Andy Kim (D-NJ): The New Jersey congressman is favored to win the seat long held by Bob Menendez (D), who resigned in August.
• John Curtis (R-UT): The Utah congressman emerged from a four-candidate primary to replace retiring Sen. Mitt Romney (R).
• Adam Schiff (D-CA): The former California prosecutor was the lead House impeachment manager in Trump’s first Senate trial. Schiff is favored to win the seat once held by Dianne Feinstein (D).