Sen. Ted CruzTed CruzSenate passes dozens of bills on way out of town Senate passes stopgap funding bill, averting shutdown Senate advances funding measure, avoiding shutdown MORE (R-Texas) took a veiled swipe at Sen. John McCainJohn McCainSecond Dem calls for probe into Russian election involvement Schumer calls for Senate probe into Russian interference Ukrainians made their choice for freedom, but now need US help MORE (R-Ariz.) in a GQ profile released Monday, saying he was “embarrassed” to have voted Republican in 2008.

“I don’t know a conservative who didn’t feel embarrassed voting in 2006 or 2008,” Cruz said. “I think the Republican Party lost its way. We didn’t stand for the principles we’re supposed to believe in.”

McCain was the Republican presidential candidate in 2008. Former Alaska Gov. Sarah Palin, who endorsed Cruz in his 2012 Senate campaign, was McCain's running mate. 

McCain and Cruz have been locking horns since the combative Texas Republican first arrived in the Senate. The two have been openly critical of one another on a range of issues, including drone strikes, foreign policy and the nomination of Defense Secretary Chuck HagelChuck HagelLobbying World Ex-Dem leader: Clinton should include GOP in Cabinet Even Steven: How would a 50-50 Senate operate? MORE.

McCain, at one point, referred to Cruz and fellow Tea Party favorite Sen. Rand PaulRand PaulTrump stumps for Louisiana Senate candidate ahead of runoff Giuliani won't serve in Trump administration Will justice in America be Trumped? MORE (R-Ky.) as “wacko birds.”

“He [expletive] hates Cruz,” a McCain aide says in the GQ profile.

McCain and Cruz are presently at odds over Cruz’s attempt to defund the president’s healthcare law. Cruz and some Tea Party lawmakers are threatening a government shutdown, saying that any resolution to continue funding the government must not include money to implement ObamaCare.