Former Massey Energy CEO Don Blankenship, Republican U.S. Senate candidate from West Virginia, waits to speak during a town hall campaign event in Huntington, West Virginia, U.S., on Thursday, Feb. 1, 2018.

Republicans fighting to hold Congress will learn something Tuesday about their party's capacity for self-control.

In West Virginia, a critical target for preserving their Senate majority, Republican primary voters are considering a wealthy coal executive who recently completed a prison term resulting from his role in a mine explosion that killed 29 people. The executive, Don Blankenship, has smeared Senate GOP leader Mitch McConnell and his "China person" in-laws in a crude campaign he calls "Trumpier than Trump."

A Blankenship victory, which polls suggest is possible, would improve the chances that vulnerable Democratic Sen. Joe Manchin could hold his seat in November's general election. And it would signal anew, as 2018 primaries begin in earnest, that President Donald Trump has helped revive the penchant for self-inflicted wounds that limited GOP gains in Obama-era Senate campaigns.

In 2010 and 2012, the weak Senate nominees who emerged from GOP primaries in states such as Nevada, Missouri, Indiana and Delaware helped Democrats extend control of the chamber. In 2014, the GOP rallied behind McConnell's efforts to advance more electable candidates and regained the majority.

But now the rank-and-file voters who responded to Trump's gut-level appeals are considering new primary choices in a GOP under the president's control. Their decisions, in lower-profile House races as well as more conspicuous Senate contests, will shape the party's ability to resist the Democrats' national momentum this fall.