With the first contest of the presidential season only a couple of weeks away, Sens. Marco Rubio and Ted Cruz aren't pulling any punches anymore.
Rubio, the Florida lawmaker who has prided himself this campaign season on focusing on the issues, has challenged Cruz's sincerity and accused the firebrand Texas senator of being a flip-flopper.
"Ted has had a tough week," Rubio said during a campaign stop in new Hampshire, according to the New York Times. "Because what's happening now is people are learning more about him."
Rubio brought up a time last year on the Senate floor when Cruz first voted against a crop insurance bill and then quickly reversed his vote to endorse it.
"He voted against it. And then someone told him, ‘Hey, you know, they are not going to like that in Iowa,'" Rubio said. "Fifteen, 20 minutes later, he came back and flipped his vote on that."
Cruz has defended this vote by saying that he was confused over which bill he was voting on at the time.
Rubio's attacks on Cruz ramped up last week during the Fox Business Network's GOP debate in South Carolina, in which the two senators went back and forth on the hot-button topic of immigration.
That dynamic continued during Rubio's trip through the Granite State.
"He's out there attacking everybody on immigration," Rubio said at a campaign stump, "but he was the one that was in favor of legalizing people who were here illegally and in favor of expanding, by 500 percent, the number of guest workers we bring into United States. He's the one who wanted to double the number of green cards from what we offer now."
For his part, Cruz has been saying that the Republican establishment – long seen as Rubio's base of support – has abandoned him in favor of billionaire businessman Donald Trump.
"We're seeing the Washington establishment abandoning Marco Rubio and unifying behind Donald Trump," Cruz said during his own tour through New Hampshire, according to USA Today. "And we're seeing conservatives coming together and unifying behind our campaign. And if conservatives unite, we win."
The Rubio camp played down Cruz's comments – echoing the candidate's message on the stump that Cruz will do anything to curry political favor
"This is more evidence that Ted Cruz is willing to say and do anything if he thinks it'll help him politically," Rubio spokesman Jahan Wilcox told USA Today. "If he turned on the TV in Iowa or New Hampshire, he'd see the real alliance in this race is the Bush and Cruz super PACs attacking Marco."
Cruz, who has seen his lead in the early battleground state of Iowa disappear, has also been on the defensive with his attacks against Trump.
"Let me encourage other members of the establishment: Keep supporting Donald Trump," Cruz said. "Because every time you do it, what it is doing is telling conservatives all over the country where you stand and who stands with you."