There are eight states holding primaries for U.S. Senate this month. Additionally, on May 5, Ohio is holding a primary for the special election to fill the rest of the six-year term that Vice President J.D. Vance (R) was elected to in 2022. 

Eight Democratic primaries and eight Republican primaries are contested this month.

Republicans hold seven of the nine seats with primaries this month, and Democrats hold the other two. Here’s a look at some notable Republican Senate primaries happening this month and how they fit into this year’s overall landscape of U.S. Senate elections. 

May 16 Louisiana primary

Incumbent Bill Cassidy (R), Louisiana Treasurer John Fleming (R), and U.S. Rep. Julia Letlow (R) lead in fundraising and polling.

U.S. Sen. Tim Scott (R-S.C.) and U.S. Sen. John Thune (R-S.D.) endorsed Cassidy. U.S. Rep. Paul Gosar (R-Ariz.) endorsed Fleming. President Donald Trump (R) and Gov. Jeff Landry (R) endorsed Letlow.

Cassidy has been in the U.S. Senate since 2014. Before that, he was a state senator and served in the U.S. House. Fleming represented Louisiana's 4th Congressional District from 2009 to 2017 and was Trump's deputy chief of staff at the end of Trump's first term. Letlow represents Louisiana's 5th Congressional District. She was a university professor and administrator before her election to the U.S. House in 2021.

May 19 Alabama primary

Jared Hudson (R), Steve Marshall (R), Barry Moore (R), and three other candidates are running in the Republican primary. Incumbent Tommy Tuberville (R) is running for governor.

Hudson is the CEO of two organizations — the Covenant Rescue Group and The Shooting Institute. Marshall is Alabama’s attorney general, and Moore is a member of the U.S. House representing Alabama’s 1st Congressional District.

Former U.S. Sen. Markwayne Mullin (R-Okla.) and U.S. Sen. Tim Sheehy (R-Mont.) endorsed Hudson. The Alabama Farmers Federation and Associated Builders and Contractors of Alabama endorsed Marshall. Trump and Vance endorsed Moore.

May 19 Georgia primary

U.S. Rep. Earl Carter, U.S. Rep. Mike Collins, real estate agent John Coyne, football coach Derek Dooley, and pastor and retired U.S. Army reserve brigadier general Jonathan McColumn are running in the Republican primary.

The winner of the primary will run against incumbent Jon Ossoff (D) in the general election.

May 19 Kentucky primary

U.S. Rep. Andy Barr, former Attorney General Daniel Cameron, entrepreneur Nate Morris, and nine others are running in Kentucky’s Republican primary. Incumbent Mitch McConnell (R) is not running, meaning the seat is open for the first time since McConnell's election in 1984.

Here are a few of each candidate’s noteworthy endorsements:

• U.S. Sen. Ted Budd (R-N.C.), former U.S. Sen. Markwayne Mullin (R-Okla.), U.S. House Majority Leader Steve Scalise (R-La.), and U.S. Rep Hal Rogers (R-Ky.) have endorsed Barr. 
• Kentucky State Sen. Gary Boswell (R), Kentucky State Sen. Robby Mills (R), and Kentucky Right to Life have endorsed Cameron.
• U.S. Sen. Jim Banks (R-Ind.), U.S. Sen. Bernie Moreno (R-Ohio), Ohio Gubernatorial candidate Vivek Ramaswamy (R), and Turning Point Action have endorsed Morris.

May 26 Texas Runoff

On May 26, incumbent John Cornyn and Texas Attorney General Ken Paxton will face each other in the primary runoff for Texas’ U.S. Senate nomination. Cornyn and Paxton advanced to a runoff because neither received more than 50% of the vote in the March 3 primary. Cornyn led Paxton 42% to 40.5% in the primary.  The winner of the runoff will face Democratic nominee and state Rep. James Talarico on Nov. 3. 

Senate Majority Leader John Thune (R-S.D.) and the National Border Patrol Council endorsed Cornyn. U.S. Reps. Lance Gooden (R-Texas) and Troy Nehls (R-Texas) endorsed Paxton.

Other Senate elections + Context

There are also U.S. Senate primaries in Nebraska (5/12), West Virginia (5/12), Idaho (5/19), and Oregon (5/19) this month. 

Thirty-three U.S. Senate seats are up for election this year and another two seats are up for special election. Nationally, Democrats hold 13 of the seats up for election, and Republicans hold 22.

The Senate seat in Maine is the only one that Republicans are defending in a state that Kamala Harris (D) won in the 2024 presidential election. Democrats are defending two seats in states that Donald Trump (R) won in the 2024 presidential election: Georgia and Michigan.

Heading into the 2026 elections, Republicans held a 53-45 majority in the chamber and both independent U.S. senators — Bernie Sanders (I-Vt.) and Angus King (I-Maine) — caucus with the Democrats.