What's the most expensive Senate race? Billions of dollars poured in for these candidates

With Election Day around the corner, hundreds of millions of dollars have been spent by candidates and outside groups across the U.S. vying to influence Senate races.

Democrats hold a thin majority in the Senate at 51-49. This year, 34 seats in the Senate are on the table, including a special election in Nebraska.

Ohio, Pennsylvania, Montana, Texas, and Michigan are among the most-watched races nationally, as they could flip the chamber from a Democratic majority to a Republican one. The Senate races are among the most expensive, all ranking within the top ten according to figures from OpenSecrets.

Here are the Senate races ranked from the most to least expensive.

The figures for the following ranking were sourced from OpenSecrets. Incumbent candidates are italicized with their party affiliation noted next to their name.

1. Ohio: Sherrod Brown (D) vs. Bernie Moreno (R)

• Total money spent: $404,890,648
• Money spent from outside groups: $283,545,814
• What to know: Incumbent Sen. Sherrod Brown is running for his fourth term, holding his seat since 2007. Brown’s opponent is Ohio businessman Bernie Moreno, who had a failed Senate run in 2022.

2. Pennsylvania: Bob Casey (D) vs. Dave McCormick (R)

• Total money spent: $289,130,166
• Money spent from outside groups: $213,963,671
• What to know: The same as Brown in Ohio, Casey is also running for his fourth term in the U.S. Senate. The Republican candidate in Pennsylvania is Dave McCormick, the former CEO of Bridgewater Associates, one of the world’s largest hedge funds.

3. Montana: Jon Tester (D) vs. Tim Sheehy (R)

• Total money spent: $260,636,099
• Money spent from outside groups: $155,501,692
• What to know: Another third-term Senator running for another term, Democrat Jon Tester is challenged by Republican Tim Sheehy, a newcomer to Montana politics.

4. Texas: Colin Allred (D) vs. Ted Cruz (R)

• Total money spent: $199,454,872
• Money spent from outside groups: $45,875,795
• What to know: Republican two-term Sen. Ted Cruz is vying to win reelection in a state that has not elected a Democratic statewide candidate in almost three decades. His challenger, Democrat Colin Allred, is a current member of the House of Representatives and a former NFL player.

5. Michigan: Elissa Slotkin (D) vs. Mike Rogers (R)

• Total money spent: $187,986,848
• Money spent from outside groups: $124,424,764
• What to know: In a race without an incumbent, Democrats and Republicans are jostling to claim the open Senate seat in Michigan. Elissa Slotkin is the current Representative for Michigan's 7th District, while the Republican candidate is Mike Rogers, the former Representative for Michigan's 8th District.

6. Wisconsin: Tammy Baldwin (D) vs. Eric Hovde (R)

• Total money spent: $180,757,988
• Money spent from outside groups: $105,485,993
• What to know: Two-term Sen. Tammy Baldwin is running against Madison, Wisconsin, businessman Eric Hovde, who previously ran for the Senate in 2012. Hovde was defeated by former Gov. Tommy Thompson.

7. Nevada: Jacky Rosen (D) vs. Sam Brown (R)

• Total money spent: $157,329,084
• Money spent from outside groups: $92,673,749
• What to know: Democrat Jacky Rosen is looking to win a second term in the Senate after winning her seat during the 2018 midterms. Her challenger is a Republican Sam Brown, who served in the Army during the Afghanistan War. He previously sought a seat in the Texas House of Representatives before moving to Nevada.

8. Arizona: Ruben Gallego (D) vs. Kari Lake (R)

• Total money spent: $156,049,777
• Money spent from outside groups: $73,681,966
• What to know: Both Gallego and Lake are vying to fill the seat left vacant by outgoing Sen. Kyrsten Sinema. Gallego is a current member of the House of Representatives while Lake is a former TV anchor and has had previous failed bids at elected office.

9. Maryland: Angela Alsobrooks (D) vs. Larry Hogan (R)

• Total money spent: $146,298,442
• Money spent from outside groups: $44,957,302
• What to know: Angela Alsobrooks, the current County Executive for Prince George's County, is facing off against former Gov. Larry Hogan, a Republican, who served in the seat from 2015 to 2023.

10. California: Adam Schiff (D) vs. Steve Garvey (R)

• Total money spent: $136,656,949
• Money spent from outside groups: $22,382,214
• What to know: Schiff and Garvey are both looking to fill the vacant Senate seat in California left by Sen. Diane Feinstein, who died in 2023. Schiff was the former chair of the House Intelligence Committee during his time in Congress, while Garvey is a former MLB player, winning the MVP Award for the National League in 1974 and a World Series championship with the Dodgers in 1981.

Fernando Cervantes Jr. is a trending news reporter for USA TODAY. Reach him at [email protected] and follow him on X @fern_cerv_.