Republicans’ battle to keep the Senate majority is growing more expensive by the day.
The Senate map still strongly favors the GOP. That hasn’t changed. But intense Democratic recruiting, brutal Republican primaries and retirements are proving costly for party leaders, nudging once-safe red states into play.
Sen. Joni Ernst’s (R-Iowa) announcement Tuesday that she won’t seek reelection in 2026 is the latest twist. Ernst had been telegraphing the move for months, so it wasn’t surprising. Republicans also quickly landed a top-tier replacement in Rep. Ashley Hinson (R-Iowa). But they’re still left without an incumbent in a state Democrats plan to heavily target.
“There’s a pretty good succession plan underway right now in Iowa. I think Iowa’s going to be fine. But none of these races are ever easy,” said Sen. Steve Daines (R-Mont.), who chaired the NRSC during the 2024 cycle.
Yet consider what’s happened to the Senate landscape over the last few months, all of which have boosted the price tag for defending the GOP’s Senate majority.
In April, Texas Attorney General Ken Paxton launched a challenge against Sen. John Cornyn (R-Texas), forcing the Senate GOP establishment to embark on a rescue mission that could cost as much as $70 million for the primary alone. If Paxton wins the primary, Senate Republicans estimate the cost for the race could balloon to $200 million.
“It would be money that could and should be spent on Georgia, Michigan and New Hampshire, among other places,” Cornyn said of a scenario where Paxton won the primary.
In May, the Senate Republicans failed to persuade Georgia GOP Gov. Brian Kemp to take on Sen. Jon Ossoff (D-Ga.). Kemp, a popular sitting governor and an impressive fundraiser, is best positioned to compete financially with Ossoff, who raised more than $21 million in the first six months of 2025.
In June, Sen. Thom Tillis (R-N.C.) declared he wouldn’t seek reelection, depriving his party of a well-funded incumbent. By the end of July, Democrats landed their dream recruit, former Gov. Roy Cooper, who raised $3.4 million in the first 24 hours.
In August, former Sen. Sherrod Brown (D-Ohio) launched a comeback bid against Sen. Jon Husted (R-Ohio). Brown faces a tough path back in a state that’s been quickly trending red, but his candidacy ensures the race will be costly for the GOP. Brown raised $3.6 million in his first 24 hours.
That brings us to September and Ernst bowing out.
“An open seat in Iowa is just the latest example of Democrats expanding the senatorial map,” Senate Majority PAC spokesperson Lauren French said after Ernst’s announcement.
The GOP response. Republicans contend they’ve always been prepared for a pricey 2026 cycle. Back in February, we reported how the NRSC urged incumbents in red states to aggressively fundraise to put races to bed early.
During that Palm Beach retreat, NRSC Chair Tim Scott warned donors there that the cycle could break spending records.
Things look promising for Republicans in Michigan, another open seat. The GOP is already aligned behind former Republican Rep. Mike Rogers (Mich.), while Democrats are sparring in an increasingly messy primary. Democrats also have crowded primary fields in Iowa and Maine.
