Republican presidential candidate Ted Cruz speaks to supporters from the rear of a pickup truck during a rally outside of Draft Picks Sports Bar on Feb. 21 in Pahrump, Nev. (Ricky Carioti/The Washington Post)

NASHVILLE — Sen. Ted Cruz (R-Tex.) conceded Friday that Republican front-runner Donald Trump has "enormous momentum" and said voters in states that vote Tuesday must stop it.

"Right now, Donald Trump has enormous momentum. He’s won three out of four states,” Cruz said here at a Christian broadcasting conference. “If he continues with that momentum and powers through and wins everywhere on Super Tuesday, he could easily be unstoppable. And I think that would be a grave mistake both for the Republican Party and for the country.”

Cruz is blitzing through states that vote in the delegate bonanza known as "Super Tuesday" next week. Cruz and Rubio tag-team attacked Trump in Thursday night's debate, though much of the attention has been on Rubio's punchy performance.

The Texas Republican, who won the Iowa caucuses but came in third in both New Hampshire and South Carolina, is banking on Super Tuesday and his home state of Texas to revive his fortunes. He has called it the most important day of the presidential campaign. Winning the many Southern states that vote Tuesday has been a linchpin of his strategy.

But as Cruz said, Trump has been gaining momentum nationally after winning three voting contests in a row. Cruz's remarks here echo ones he made in Iowa to a group of pastors, warning them that they must stop Trump in Iowa. The state handed the businessman a second-place finish, but he has only ascended since then. Cruz continues to remind audiences that he is the only person in the race who has beaten Trump.

"To date only two candidates have won a state. Donald Trump and me. We are the only candidate that has beaten Donald Trump," Cruz said.

In contrast to Rubio's new line of attack against Trump, primarily hitting his business record and personality, Cruz has mostly continued with the hits on Trump he has been making for weeks, branding the businessman as a false conservative, a former liberal who donated to Democrats and supported abortion rights.

Friday, both during a taping of "Hannity" here and at the conference, Cruz started knocking Trump's business record, including a New York Times story stating that Trump hired foreign workers instead of Americans, and that he has only looked out for himself in his dealings.

"A man who has a multi-decade history of exploiting the immigration laws to take advantage of the little guy is not someone we can trust to stand with the working men and women of this country," Cruz said.

When Trump makes a deal, Cruz said, "the people who get hammered are the working men and women. He gets rich and everyone else gets left holding the bag."

Cruz brushed off New Jersey Gov. Chris Christie's endorsement of Trump.

"I think the endorsement was no doubt troubling news for the Rubio campaign," Cruz said.

"I like Chris. I don’t think the endorsement was a big surprise to many observers," he added. "Our focus is real simple: uniting conservatives on Super Tuesday. I don’t think this endorsement has any significant impact on that."