Changing demographics would seem to weaken the appeal of anti-government figures like Mr. Cruz (who was born in Canada and is of Cuban ancestry). That is why traditional conservatives like the columnist Michael Gerson insist that “pragmatic Republicans” are the party’s salvation, and that Mr. Cruz and his allies are mounting a “revolt against reality.”

But as America becomes more diverse, another population has come more clearly into view: the alienated and disenchanted. These people have embraced a libertarian and anti-government outlook and have little use for what they see as the compromised, impure “big government” conservatism of the Reagan and Bush years.

To this constituency, the Republican who will go as far as he can — taking one last crack at undoing Mr. Obama’s health care reform or voting later this month not to raise the debt ceiling — is not an obstructionist but a politician of principle, a rebel with a cause.

“The business of the opposition is to oppose,” as Robert A. Taft, the Republican senator who led the attempt to slow down New Deal programs, once said…

“‘It does not take a majority to prevail,’ ” Mr. Paul said at the conference’s climactic event, quoting Samuel Adams, “ ‘but rather an irate, tireless minority, keen on setting brush fires of freedom in the minds of men.’ ”

This is the sentiment guiding today’s post-consensus politicians, who look back even as they gird for the next battle.