Cruz, who has looked to position himself as the furthest-right candidate in the field, said in an interview with CNN on Tuesday that he appreciated that Bush, who may be the GOP's furthest to the left, was not changing his positions.
"There are candidates in the field who attempt to change their position to do better in primaries, and Jeb Bush has demonstrated a remarkable candor defending positions," said Cruz, a Texas senator. "Jeb Bush has been straightforward and consistent and candid about his embrace of amnesty and Common Core, and I respect that he is willing to stand for those principles."
A spokeswoman for Bush, Kristy Campbell, said in a statement that his plan -- which offers "earned legal status" to undocumented immigrants -- was not "amnesty."
"He will continue to stand on his principles," she said.
Cruz has at times been careful to avoid criticizing candidates harshly by name, preferring to speak in general terms about the contrast between himself and the rest of the Republican field. His backhanded compliment to Bush, the former Florida governor, mirrors what Cruz frequently says about Democratic candidate and Vermont Sen. Bernie Sanders, who he praises as an "honest" socialist, unlike Hillary Clinton, who Cruz describes as a philosophical sibling.
But Cruz is indicating a fresh willingness to go after Bush. This week he incorporated a new shot at him into his recorked stump speech, lumping him in with 2012 GOP presidential candidate Mitt Romney and President Barack Obama for criticizing Cruz's comment that Obama's nuclear deal with Iran makes him the leading state sponsor of terrorism. Shouting choice words, crowds booed at Bush's name at nearly every stop -- sometimes even more loudly than they did at Obama's.
Those mentions came as Cruz winds his way through the South, where he's hoping to score primary wins in the four states voting March 1. Cruz's advisers stress that the Texas senator is playing the long game, and the candidate himself downplayed the need for him to score a top performance in Iowa, New Hampshire or South Carolina. (Almost never mentioned at any Cruz stop: Nevada, which votes fourth.)
"In the previous election, it was possible for a candidate to go move to Iowa for a year, live there, and hope to capture lightning in a bottle, surprise everyone and ride that momentum and possibly win the nomination. I think the accelerated calendar makes that much less likely this time," Cruz said as his bus ambled from Olive Branch, Mississippi over the Tennessee border. "Of the 17 Republican candidates, there are only a handful capable of running a national campaign."
That "national campaign" suggests that Cruz would remain in the GOP primary until late into the spring -- and possibly even the early summer. Cruz has begun to organize in states as deep into the primary calendar as New Jersey, which votes in June, only weeks before the Republican National Convention meets in Cleveland.
"A brokered convention is certainly possible, but if history is any guide, it's quite unlikely," he said.