Buchanan, now 80, is a conservative pundit and former White House adviser who challenged President George H.W. Bush in the 1992 GOP primary, foreshadowing the rise of Trump populism. Buchanan was a long shot from the outset and never seriously threatened Bush for the nomination. But his campaign proved a major irritant and is partly credited with weakening the incumbent and boosting the inevitable victor, Bill Clinton, in the general election.

In 2020, that is the sort of primary challenge some “Never Trump” Republicans envision pursuing against this president if their favored option — running a contender strong enough to win — doesn’t come to fruition. For Republicans committed to dislodging Trump at all costs, wounding him in a primary would be adequate. No president challenged for renomination in the modern era has won a second term.

“For a number of people I’ve spoken to, putting a torpedo into Trump’s operation would suffice for them — if they could mortally wound him in a primary,” said a Republican insider involved in the effort.