To see the importance of recruiting credible, well-funded candidates, one need only look back to November and the Virginia legislative races, where Democrats nearly won a majority in the House of Delegates after almost 20 years in the minority. Those gains were only possible because Democrats fielded an impressive array of candidates for a slew of low-profile, down-ballot races, turning formerly “red” districts into competitive ones.

For 2018, Democrats have not had trouble fielding challengers for races up and down the ballot, from congressional elections to contests for control of statehouses and governor’s mansions. Republicans, on the other hand, are struggling to find viable candidates for even some of the party’s most promising races, including states won by Donald Trump in the presidential election. And the reason is clear: Thanks to President Trump, it’s a bad time to be an ambitious Republican politician.

Even at this early stage in the election cycle, all signs point to some form of a Democratic wave in November, fueled by broad and intense opposition to Trump and his allies.

For Republicans mulling a run this year, the landscape is ominous. There’s the congressional generic ballot, a simple but reliable survey question that asks voters which party they would prefer have control of Congress. Once you adjust for which party controls the White House, notes Harry Enten of FiveThirtyEight, the generic ballot is “strongly correlated” with the eventual results as early as 18 months before the election. In 2006, when Democrats took the House and Senate, they held a roughly 10 percentage point average lead in the generic ballot. As of this week, according to Real Clear Politics, they have an average lead of roughly 8 percentage points, with individual polls that range from modest leads of 5 points to substantial ones of 12 or 14 points.

There’s also anecdotal evidence from a collection of special and off-year elections. Last year, Democrats won 14 special elections in Republican-held state legislative districts, in addition to a historic upset in the Alabama Senate race. While Democrats weren’t able to prevail in some deep-red places like Georgia’s 6th Congressional District, they have consistently overperformed in election after election since Trump’s victory. On average, according to left-leaning analysts at the website Daily Kos, Democrats are outperforming past results by around 10 points.

If the environment is fertile for Democratic prospects, it is treacherous for their Republican counterparts, who have struggled to recruit the kinds of candidates who could hold competitive seats or strike at vulnerable ones. Ohio Sen. Sherrod Brown is a liberal Democrat in a state Trump won by nearly 9 percentage points. By any measure, he is a vulnerable incumbent. And yet, Ohio Republicans have yet to field a top-tier challenger. State Treasurer Josh Mandel—who faced Brown in 2012—dropped out of the race earlier this month, citing family concerns. Hillbilly Elegy author JD Vance—a Republican with ties to the party establishment in Washington—declined to step into the ring after discussing a possible run with Senate Majority Leader Mitch McConnell. Thus far, the only challengers to Brown are Rep. Jim Renacci and Mike Gibbons, a self-financing Ohio businessman. There’s still no guarantee that Sen. Brown will win reelection, but in the absence of strong, high-profile challengers, his odds have gone up.

In Virginia, Sen. Tim Kaine is up for re-election. Compared to Ohio, it presents a more difficult political test for Republicans. Hillary Clinton held Virginia’s Electoral College votes, and Democrats swept statewide elections last November. Still, the state is roughly divided between the two parties, and there’s no shortage of credible Republicans in the commonwealth. But only two candidates have stepped up so far to challenge Kaine: Corey Stewart, a Northern Virginia politician whose campaign of white racial resentment nearly toppled Ed Gillespie in the Republican gubernatorial primary; and E.W. Jackson, a far-right minister who ran unsuccessfully for lieutenant governor in 2013.

Likewise, in Minnesota, Republicans haven’t been able to recruit a candidate for the Senate seat once held by Al Franken and now occupied by Tina Smith, who previously served as lieutenant governor. The state is trending toward the GOP, and the scandal around Franken gave Republicans a chance to wring a seat from Democratic hands. But one of the most high-profile Republicans in Minnesota, former Gov. Tim Pawlenty, has already said he won’t run, rebuffing party leaders, donors, and conservative activists.

The problem is compounded by the growing pace of retirements among Republicans in the House, many in swing districts that could easily fall to Democrats in the absence of a strong Republican effort. Facing a potential wave, Republicans need credible candidates; the fewer they have, the higher the odds of a genuine wipeout that consumes GOP majorities in the House and the Senate.

There are nearly 10 months between now and the midterm elections. As we saw in the 2016 election, there is a lot that can happen in that. But it’s also not that long, and if Republicans can’t solve their recruitment problem soon, they may end up with an even worse electoral landscape than they first imagined.