At the end of an hourlong event in West Virginia on Thursday, Donald Trump polled the crowd about whom they would like to see win next month’s Republican primary for U.S. Senate. “Should we do a little test?” asked the president, who was flanked by the two establishment-approved candidates, state attorney general Patrick Morrisey and U.S. Rep. Evan Jenkins. “Who’s voting for Patrick? Who’s voting for Evan?”

Noticeably absent from the stage was a third candidate for the GOP nomination, one with far more money and name recognition: Don Blankenship, the coal baron and ex-con who the Republican establishment fears will spoil their chances of defeating Democratic Sen. Joe Manchin this fall in a state Trump won by more than 40 percentage points in 2016.

When Blankenship jumped into the race last fall, many wondered whether his motivation was less about the Senate and more about rehabbing his image after spending a year in prison in connection with a 2010 explosion at one of his mines that killed 29 men. But only a month out from the May 8 primary, Blankenship has emerged as a top GOP contender in a race that could help decide control of the Senate.

According to internal polls released by both Morrisey and Jenkins last month, Blankenship is in a virtual tie for first in the primary, though whom he is tied with depends on who you ask. Morrisey’s pollsters found their candidate in front with 24 percent, followed closely by Blankenship with 23 percent, and Jenkins with 17. Jenkins’ pollsters, likewise, found their own man leading with 29 percent, followed by Blankenship with 27 percent, and Morrisey with 19.

That Blankenship is even in the running is remarkable. It was only three years ago that his lawyer was arguing that he couldn’t get a fair trial in West Virginia given his standing in the state, and less than a year ago that Blankenship was still in a halfway house finishing out his sentence after being convicted in 2015 of conspiring to violate federal mine safety standards in connection with the devastating 2010 explosion at the Upper Big Branch coal mine—the worst mining disaster in 40 years, according to the federal government.

But according to Blankenship, that disaster and his conviction are reasons to vote for him, as he’s merely an innocent victim of the liberal war on coal. After his conviction, he penned a 67-page manifesto declaring himself a “political prisoner” of the Obama administration. After his release, he paid for ads alleging that it was federal regulators who were really to blame for the blast. Fittingly, he compared the supposed cover-up to Benghazi. As Kevin Robillard pointed out in Politico magazine last week, it’s no wonder, then, that Blankenship has found a sympathetic audience among an increasingly conspiracy- and persecution-minded GOP base.

The Republican establishment, of course, has no problem with conspiracy theories when they serve its purpose. But Blankenship appears to be an exception given West Virginia’s importance in the GOP’s midterm strategy, and his own history in the state, which includes plenty of controversy even before the Upper Big Branch blast turned him into the Dark Lord of Coal Country. The problem for Republicans, though, is that it’s not clear what they can do to stop Blankenship—a puzzle that has become increasingly common for a party that has a number of controversial, Trump-like insurgents threatening to spoil its dreams in key races across the country, from Arizona to Mississippi.

Mitch McConnell is on record that he doesn’t want Blankenship as the nominee, but so far Senate Republicans and the White House are treading carefully. They fear that if they attack Blankenship directly, they’ll only boost his anti-establishment bona fides in a possible repeat of what happened in Alabama last year, when Trump and the establishment tried and failed to stop Roy Moore from getting the nomination. But passive-aggressive attacks like not inviting Blankenship to the president’s events are unlikely to accomplish much on their own, particularly considering Blankenship is spending big on campaign ads that pledge allegiance to Trump. Making matters worse for the GOP is that they are either unwilling or unable to pick a favorite among Blankenship’s challengers, which could prevent either from consolidating the non-Blankenship vote on primary day.

On Thursday, Trump offered a few kind words about both Morrisey and Jenkins after they had heaped praise upon him at his urging, but the president went out of his way to avoid picking a favorite. At one point he lumped them together as “two very smart and very good representatives of you folks.” Then at the end of the event, he declined to declare a winner of his applause-based poll after Jenkins drew the louder cheers and Morrisey pointed out they were in his opponent’s district. “Well, it was fairly close,” the president said with a laugh. Trump and the GOP won’t be laughing if neither Morrisey nor Jenkins finds a way to pull ahead soon.