Republicans lost their only serious candidate to challenge Sen. Sherrod Brown (D-OH) on Friday, as state Treasurer Josh Mandel (R) issued a surprise statement dropping out of the race.

“We recently learned that my wife has a health issue that will require my time, attention and presence. In other words, I need to be there,” Mandel said in a statement to supporters. “Understanding and dealing with this health issue is more important to me than any political campaign.”

The shock decision leaves state Republicans scrambling for a top-tier candidate to face Brown in a state that President Trump easily carried last fall. But even before Mandel dropped his campaign, it was looking like an uphill battle for the GOP to unseat Brown, a populist warrior whose numbers have remained strong in the state.

“Ohio’s looking a lot like the rest of the nation in terms of the overall political environment. It’s going to be a tough race, Sherrod Brown’s going to be well funded and maybe that made the decision for Josh easier and maybe makes the decision for others harder to get into this,” former Ohio Republican Party Chairman Kevin DeWine told TPM shortly after Mandel’s announcement.

Mandel had backing from the establishment and tea party wings of the GOP, and had appeared likely to cruise to nomination after other top Republicans took a pass on the race. But his decision to drop out may not be a major setback for the party. Brown defeated Mandel in 2012 by 51 percent to 45 percent, running ahead of President Obama, and Mandel had exposed his flaws as a candidate in that campaign.

Republicans are looking at a crowded primary field for governor, and either Rep. Jim Renacci (R-OH), Ohio Lt. Gov. Mary Taylor (R) or Ohio Attorney General Mike DeWine (R) could decide to slide over to a Senate race, as could Ohio Secretary of State Jon Husted (R), who’s currently running for lieutenant governor. Rep. Pat Tiberi (R-OH) also had spent much of the past year testing the political waters, but is leaving Congress in a matter of weeks to head the Ohio Business Roundtable, a job he’s unlikely to back out of. Businessman Mike Gibbons is the only Republican left in the race at this point.

But whoever wants a crack at Brown better hurry: The filing deadline for the primary is just a month away, on Feb. 7, and candidates will need to hustle to gather enough petition signatures to get on the ballot.