Some in the old guard have started signaling to their reluctant right-of-center brethren that it is time to face the possibility that the hard-line Mr. Cruz could be their standard-bearer.

“If Cruz makes it, which is very doable, every one of the establishment crowd who is now eviscerating him will line up, salute smartly and get on board,” Ms. Matalin said, offering a mix of prodding and prophecy. “No one will want to be responsible for a G.O.P. defeat.”…

What is more striking, and will cause deep consternation among Republican strategists, is that other donors are beginning to embrace Mr. Cruz’s argument that he can win a general election by motivating core conservatives to come to the polls rather than by appealing to swing voters.

Andrew Puzder, chief executive of the conglomerate that owns Hardee’s and Carl’s Jr., supported both of Mr. Romney’s campaigns and has contributed to a number of “super PACs” and candidates this year, including Jeb Bush and Senator Marco Rubio of Florida. But after spending a couple of hours eating brisket with Mr. Cruz on Sunday at his campaign headquarters, Mr. Puzder said he was “very seriously considering” getting behind him, in part because of his appeal to the conservative base.