While the race for the White House between Kamala Harris and Donald Trump commands the most attention before Election Day, the outcome of the 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 grabs this year, and Democrats are looking to topple the current 220-212 Republican majority. Meanwhile, 34 Senate seats are up for grabs as Republicans seek to win control of the upper chamber while Democrats hold a slim 51-49 majority.

If Trump wins, his presidential powers and the GOP 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 choose their next governor, who will have a more direct impact on their daily lives on major policy issues like abortion rights, taxes and immigration.

Here are some of the key congressional and downballot races to watch:

Senate races to watch

Democrats and four independents who join them currently hold a slim 51-49 majority in the Senate and are on the defensive in this election. If Harris wins, Democrats can afford to drop one seat and keep their majority. If Trump wins the election, Democrats must retain all of their current seats to maintain their majority. If elected vice president, Republican Sen. JD Vance of Ohio would become the tiebreaker for the Senate.

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

  • Why it matters: Joe Biden flipped Arizona in the 2020 election and is considered a battleground state in 2024. Incumbent Sen. Kyrsten Sinema (Independent) opted not to run for re-election, so her seat is put into play.

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

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

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

  • Why it matters: While Biden won the deep blue state in 2020, it’s a surprisingly close race for an open Senate seat. Incumbent Sen. Ben Cardin (D) has decided not to run for re-election.

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

  • Why it matters: 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 retiring Democratic Sen. Debbie Stabenow is billed as a “revenge” by by Cook Political Report.

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

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

  • Why it matters: While Trump won the state in 2020, incumbent Fischer is in a close race with Osborne.

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

  • Why it matters: In 2020, Biden won Nevada. In 2022, the governor’s office went from a Democrat to a Republican. Rosen is defending his seat as the incumbent.

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

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

• Texas: Sen. Ted Cruz (R) vs. Rep. Colin Allred (D)

• Wisconsin: Sen. Tammy Baldwin (D) vs. businessman Eric Hovde (R)

  • Why it matters: In a 2024 battleground state that Biden flipped in 2020, the Cook Political Report rates this race as “throw up.“

House races to watch

All 435 seats in Parliament are up for re-election on November 5. Republicans hold a slim majority of 220 seats, while Democrats hold 212 seats. Three seats are vacant: Wisconsin’s 8th District is expected to remain Republican after GOP Rep. Mike Gallagher resigned from Congress. New Jersey’s 9th and 18th districts in Texas are expected to remain Democratic after the 2024 deaths of Democratic Reps. Bill Pascrell and Sheila Jackson Lee.

If that happens, Democrats would need to gain four more seats to gain a majority in the House. Democrats have an opportunity to flip 19 Republican-held seats that Biden won in 2020. Of the 19, these are the nine listed as “eliminations” by Cook Political Report.

“Throws” organized by Republicans

• Arizona

• California

  • 13th District: John Duarte (R) vs. Adam Gray (D)

  • 22nd District: David Valadao (R) vs. Rudy Salas (D)

  • 27th District: Mike Garcia (R) vs. George Whitesides (D)

  • 45th District: Michelle Steel (R) vs. Derek Tran (D)

• new york

• Oregon

With Republicans on the defensive in the House, there are eight Democratic-held districts that Trump won in 2020 that the GOP could flip. Of the eight, these are the four highly competitive races listed as “throw up” by the Cook Political Report:

Democrat-backed “dumps.”

• Alaska

• Tomorrow

• Pennsylvania

• Washington

Government races to watch

Eleven gubernatorial races are on the 2024 ballot. Eight of those races have vacancies. Of those, the Cook Political Report shows Delaware voting solidly for the Democratic nominee, while Missouri, Montana, North Dakota, Utah, Vermont and West Virginia are likely to vote solidly Republican. The following government races are those that are considered competitive.

“Throw”

“Probably” Democrat.

“Probably” Republican