ATLANTA — With Super Tuesday approaching, Marco Rubio and Ted Cruz escalated their argument Saturday that Donald Trump is a conservative impostor, trying to make the case to voters they can keep the ascendant billionaire from claiming the Republican presidential nomination.

At a rally outside the Georgia Capitol, Cruz went after Trump's positions on immigration and gun control, criticized his ethics and hammered him for his frequent use of profanity.

“You don't know what he's going to say,” Cruz told reporters. “To the parents: Would you be proud of your children if they came home and repeated the words of Donald Trump?”

Rubio kept up a barrage of insults aimed at Trump. Speaking at a football stadium at Mount Paran Christian School in suburban Atlanta, Rubio said Trump has “the worst spray tan in America.”

“Donald Trump likes to sue people,” Rubio said. “He should sue whoever did that to his face.”

The quip drew laughs.

Rubio quickly turned to immigration and kept up his criticism that the real estate mogul has employed people living in the country illegally.

Georgia is one of 11 states that will hold GOP presidential primaries Tuesday, when 595 delegates will be at stake.

Super Tuesday is the biggest single-day delegate haul of the nomination contests and, says Cruz, “the single best opportunity to defeat Donald Trump.”

Democrats also vote in 11 states, as well as in American Samoa.

In Tennessee, Ohio Gov. John Kasich won the endorsement of former U.S. Attorney General Alberto Gonzales, now dean of Belmont University's law school.

Trump, the GOP front-runner who has won three states in a row after losing in Iowa's caucuses to Cruz, held a campaign rally in Arkansas with Chris Christie, the New Jersey governor and former presidential candidate.

“This guy has a fresh mouth,” Trump said of Rubio.

On Saturday, Rubio also released summaries of his last five years of tax filings, revealing him to be a candidate with a senator's steady annual income of $176,000 who reaped windfalls from book deals. During his four years in the Senate, Rubio and his wife Jeanette together earned an average of $531,000 a year.

The disclosure makes Rubio the only one of the top three Republican candidates to fulfill pledges to disclose tax information.