Ohio Treasurer Josh Mandel, a Republican, unexpectedly dropped his challenge to incumbent Sen. Sherrod Brown, D-Ohio, on Friday, citing his wife’s health issues and at once creating the biggest political vacuum of 2018.

The eloquent and well-known state treasurer had all but locked down the GOP primary. According to a December Ohio Freedom Fund poll of 500 likely Republican voters, Mandel was untouchable with 52 percent of the vote. His only declared competitor, a Cleveland banker and GOP donor named Michael Gibbons, brought in a measly 5 percent.

Now with just four months to go ahead of the May 8 primary, the nomination is completely up for grabs. Obviously, this is a major disappointment and significant worry for Republicans.

Ohio presented a solid opportunity for a Senate pickup. President Trump won the state by a surprising 8 percentage points in 2016, and Mandel lost to Brown by 6 points in 2012. What’s more, that victory has been the only state-wide success for Democrats in more than a decade. The right candidate with the right message could turn Ohio red in 2018, but apparently that candidate won't be Mandel.

Now, Republicans will scramble if they’re going to find a champion. The one man still standing is Gibbons. A mega-donor, he is good at fundraising. But without a race to his name, he is a political rookie.