Series of shakeups roil the 2026 Senate primary elections; GOP tries to hold majority

A series of shakeups have rocked the 2026 Senate primary election process for both parties, as the GOP tries to hold its majority in the chamber. 

Two of the 22 Republican seats up for reelection in 2026 are in states that Trump either won or lost by less than 10 points in 2024, Politico has noted. Republicans currently occupy 53 seats in the Senate compared to 45 for Democrats plus two independents who caucus with Democrats.

One of the most significant developments involves Maine Democratic Gov. Janet Mills who is officially entering the Democratic primary to challenge longtime Republican U.S. Sen. Susan Collins.

A University of New Hampshire poll from April 2025 found that 71% of Maine voters thought Collins did not deserve re-election in 2026. The same poll found Mills to be the preferred challenger to Collins, making the race a crucial one to watch.

Graham Platner, another Democratic primary challenger to Collins, has dealt with controversy due to his since-deleted Reddit posts from several years ago. The progressive candidate wrote on Reddit that “white people aren’t as racist or stupid as Trump thinks."

In another, he referred to himself as “a vegetable growing, psychedelics taking socialist these days.”

Platner said he regrets the posts and is remaining in the race.  

Issues across the states

Jon Bel Edwards, former governor of Louisiana, decided this week not to challenge incumbent Sen. Bill Cassidy, R-La. 

“After eight years in the Governor’s Office, and with two grandbabies at home, we’re committed to being the best Papa and Nonna we can be,” Edwards, 59, said.

Edwards was considered a likely challenger to Cassidy, given his ability to win two terms as a Democratic governor in a red state.

At this time, a Democratic challenger to Cassidy has not yet emerged. 

State Treasurer John Fleming, state Sen. Blake Miguez and Public Service Commissioner Eric Skrmetta are GOP candidates that are running against Cassidy.

Cassidy, currently serving as the chair of the Senate Health, Education, Labor, and Pensions (HELP) Committee, currently holds the edge in his primary, raising more money so far than his challengers at around $10 million, according to reports.

“I’m deeply grateful for the support from Louisianians in every corner of our state,” Cassidy said in his statement. “I thank all those from across our state who see that my work for Louisiana and with President Trump is delivering results for individuals, families and Louisiana."

Cassidy has faced some backlash from Trump supporters over his vote to convict Trump during his 2021 impeachment trial.

Cassidy has defended his conservative record, citing his votes to confirm two key Trump cabinet secretaries for the president's second term.

"(Trump) has got two cabinet secretaries he would not have unless I'd gotten them approved," Cassidy said, referring to Health Secretary Robert F. Kennedy Jr. and Defense Secretary Pete Hegseth.