While the race for the White House between Kamala Harris and Donald Trump is demanding the most attention ahead of Election Day, the outcome of Congressional elections could determine the success of a Harris or Trump presidency.

All 435 seats in the U.S. House of Representatives are up for reelection this year, and Democrats are looking to upend the current 220–212 Republican majority. Meanwhile, 34 Senate seats are up for grabs, including one special election in Nebraska, as Republicans are looking to gain control in the upper chamber as Democrats hold on to a razor-thin 51–49 majority.

If Trump wins, his presidential powers and Republican Party agenda could be limited by a Democratic-majority House of Representatives, while a Republican-led Senate could interfere with the policy plans of a potential Harris administration.

Voters in 11 states will also select their next governor, who will have a more direct impact on their everyday lives on major policy issues like abortion rights, taxes and immigration.

State-level races that could impact the country

Your guide to where LGBTQ+ issues are on the ballot this November

Here are some of the key Congressional and down-ballot races to watch:

Senate races to watch

Democrats, and four independents who caucus with them, currently hold a very slim majority of 51–49 in the Senate and are on the defensive in this election. If Harris wins, Democrats can afford to give up only one seat and keep their majority. If Trump wins the election, Democrats must hold onto all of their current seats in order to maintain their majority. If elected vice president, Republican Sen. JD Vance of Ohio would become the Senate’s tie-breaking vote.

• Arizona: Rep. Ruben Gallego (D) vs. former TV anchor Kari Lake (R)

• Why it’s important: Joe Biden flipped Arizona in the 2020 election and it’s considered to be a 2024 battleground state. The incumbent, Sen. Kyrsten Sinema (independent), opted not to run for reelection, so her seat is up for grabs.

• Florida: Sen. Rick Scott (R) vs. former Rep. Debbie Mucarsel-Powell (D)

• Why it’s important: In a state that has consistently voted Republican in recent years, Democrats are on the offensive as Scott defends his seat in this closer-than-expected race.

• Maryland: former Gov. Larry Hogan (R) vs. Prince George’s County Executive Angela Alsobrooks (D)

• Why it’s important: While Biden won the deep-blue state in 2020, it’s a surprisingly close race for the open Senate seat. The incumbent, Sen. Ben Cardin (D), decided not to run for reelection.

• Michigan: Rep. Elissa Slotkin (D) vs. former Rep. Mike Rogers (R)

• Why it’s important: Michigan is considered a 2024 battleground state after Biden flipped it from red to blue in 2020. The race for the seat left open by Democratic Sen. Debbie Stabenow, who is retiring, is considered a “toss up” by Cook Political Report.

• Montana: Sen. Jon Tester (D) vs. Navy SEAL veteran Tim Sheehy (R)

• Why it’s important: Three-term incumbent Tester finds himself defending his seat in a state that Trump won in 2020. Cook Political Report rates this race as “leaning Republican.”

• Nebraska: Sen. Deb Fischer (R) vs. union leader Dan Osborn (independent)

• Why it’s important: While Trump won the state in 2020, incumbent Fischer finds herself in a tight race with Osborn.

• Nevada: Sen. Jacky Rosen (D) vs. Army veteran Sam Brown (R)

• Why it’s important: In 2020, Biden won Nevada. In 2022, the governor’s office flipped from Democrat to Republican. Rosen is defending her seat as the incumbent.

• Ohio: Sen. Sherrod Brown (D) vs. businessman Bernie Moreno (R)

• Why it’s important: Brown is defending his seat as the incumbent in a state that Trump won in 2020. Cook Political Report rates this race as a “toss up.”

• Pennsylvania: Sen. Bob Casey (D) vs. businessman Dave McCormick (R)

• Why it’s important: Casey is defending his seat in the 2024 battleground state that Biden flipped in 2020. Cook Political Report rates this race as a “toss up.”

• Texas: Sen. Ted Cruz (R) vs. Rep. Colin Allred (D)
• Why it’s important: The increasingly tight race is a rare instance where a Democrat is on the offensive in a deep red state that Trump won in 2020.

• Wisconsin: Sen. Tammy Baldwin (D) vs. businessman Eric Hovde (R)
• Why it’s important: In a 2024 battleground state that Biden flipped in 2020, Cook Political Report rates this race as a “toss up.”