Texas Sen. Ted Cruz claimed Florida Sen Marco Rubio has betrayed his constituents and Donald Trump has hidden his record.
Cruz responded to criticism from rival GOP presidential candidates in remarks to reporters in South Carolina.
Rubio has argued that Cruz is a calculating politician, something Cruz described as preposterous.
"When Marco went to Washington, he broke his word and promptly joined with Barack Obama and Harry Reid and Chuck Schumer to lead the fight to pass amnesty," Cruz told reporters. "You want to talk about calculated? That is the essence of calculated: Looking at the people who elected you, making a promise, and then breaking a promise. Why? Because the big money donors in Washington, because the Washington establishment supports amnesty. That was a calculated move and that was not a move that gives any comfort to the American people that they can trust a candidate to do what he says and the difference is I honored the commitment. It is not calculated for someone to do what he said he would do, to actually fight against amnesty and successfully defeat amnesty, which is exactly what we did."
"There is more than a little irony in Donald accusing anyone of being nasty, given the amazing torrent of insults and obscenities and vulgarities that come out of his mouth," Cruz said. "When you're being attacked by Donald it is always colorful. I will give him this: He's not boring. My approach has consistently been I'm not going to respond in kind. So he can launch whatever insults he wants. My focus is going to be on the substance and issues. And there is a reason that Donald engages in attacks because it's all a smoke screen to hide from his record."
Cruz made an appearance at the Faith and Family Forum in Greenville, S.C., where the senator described President Obama's response to the 2015 Charleston Church shooting as a "missed opportunity."
The Texas senator will appear with former Gov. Rick Perry of Texas and conservative radio host Glenn Beck in South Carolina next week. Cruz ranks second in the Washington Examiner's newest GOP presidential power rankings.