Faced with the demoralizing prospect of a third consecutive loss in a presidential race, conservative Republicans are girding for an extended clash on two fronts in the months ahead: one with a Hillary Clinton administration that could look like a reprise of the partisan battles of the 1990s, and another with Republican leaders on Capitol Hill who rejected Donald J. Trump.

Though a victory by Mrs. Clinton is far from a foregone conclusion, what does seem clear is that the frustrations and anxieties that fueled Mr. Trump’s rise will not be fleeting. And a defeat of Mr. Trump — which he has already darkly alluded to as part of a plot to disenfranchise his supporters — could further inflame those on the right whose goal all along has been to disrupt the country’s political system.

Some of the loudest voices on the right seem poised to channel that anger into one of their favorite and most frequent pursuits: eating their own.

Some in the deeply factionalized Republican Party, including Mr. Trump and some of his senior aides, are already fanning the flames for a revolt against the House speaker, Representative Paul D. Ryan of Wisconsin, once Congress reconvenes after the election. Mr. Trump, who has lashed out at the speaker for being critical of him, has privately said that Mr. Ryan should pay a price for his disloyalty, according to two people close to Mr. Trump who insisted on anonymity to describe internal campaign discussions.