Marco Rubio flipped the script on front-runner Donald Trump's march to Super Tuesday and the Republican presidential nomination, unexpectedly attacking the front-runner and breathing life into his underdog campaign.

The Florida senator bullied and battered the New York celebrity businessman during Thursday's televised debate and again Friday during campaign stops in Texas and Oklahoma, days before a slew state of primaries in New England and across the South. Copying Trump's playbook, Rubio mocked the billionaire personally, calling him a petty, panicky "con man" who is too ignorant to be president and would be selling watches on the streets of Manhattan if not for his inherited wealth.

"Trump's the front-runner, and we need to unite the anti-Trump vote, because we believe that it's more than 50 percent. The only way to do that is to take the fight to Trump," Rubio campaign spokesman Alex Conant told the Washington Examiner.

Rubio called Trump a "clown" Friday evening during an interview with Fox News anchor Bret Baier. "He is a guy that portrays himself as defender of the little guy in this country. He has been exploiting working Americans for 40 years. When his businesses went bankrupt, the first people who didn't get paid were those small contractors," Rubio added.

Trump won three of the first four primaries, and is still best positioned to secure the 2016 nomination.

He's favored in most states that vote in March, beginning with Tuesday's southern "SEC" primary and in states like Massachusetts and Vermont. Rubio needs to win delegates next week while contending with Trump and Sen. Ted Cruz of Texas. Rubio also faces a must-win contest in the Sunshine State on March 15, where Trump also leads. And Rubio has picked a fight with a wily competitor who rarely backs down and is adept at manipulating media coverage.

Rubio's domination of political news extended from Thursday evening's debate in Houston, into Friday morning, when the senator reprised and escalated attacks on Trump during a campaign rally in Dallas before 2,500 people that was broadcast by the cable networks. Trump responded crisply with a Friday noontime press conference in Ft. Worth, Texas, to introduce New Jersey Gov. Chris Christie and his endorsement. He then returned fire at Rubio during a rally with several thousand supporters.

"A guy like Rubio's a baby," Trump said, arguing that Rubio isn't presidential material. "He was so scared like a little frightened puppy."

Cruz and other GOP presidential contenders had previously hammered Trump for the reality television star's history of supporting liberal causes, policies and politicians. But none had attacked Trump personally — at least in a way that stuck — the way Rubio did during the debate and again on the trail on Friday. His approach is similar to the approach the New Yorker has used so effectively to neuter opponents, like when he called former presidential candidate Jeb Bush "low energy."

Since launching his campaign nearly one year ago, Rubio and his team had militantly avoided personal attacks, and generally shied away from striking first. There were exceptions. The senator initiated contrasts on policy with some of his opponents, particularly Cruz. And, if attacked, Rubio always responded, sometimes aggressively. He hasn't hesitated to call opponents "liars" in response to attacks he claims are false. Otherwise, Rubio has generally favored positive messaging over sharp contrasts.

But having failed to win any of the first four primary states, and with March around the corner and Trump close to romping a field that is still divided between five candidates, a change of strategy was in order. Republican strategists who oppose Trump lauded Rubio's new approach. Their concern is that it may have come too late to alter the trajectory of the race.

"He was effective in attacking Trump last night because he was ready for Trump's counterpunches and persisted in his attacks," Republican communications consultant Brett O'Donnell said. This "gives him effective messaging coming out of the debate, seamlessly with the rest of the campaign. I worry that it is too late."

The Rubio campaign decided that the only way to overtake Trump was to take the fight to him directly.

Rubio's team determined that this was the best way for the senator to convince anti-Trump voters to consolidate behind him, rather than Cruz, Ohio Gov. John Kasich or retired pediatric neurosurgeon Ben Carson. The campaign felt free to prosecute this strategy because with Bush and Christie out of the race, Rubio was no longer facing attacks from multiple directions. It also believed the time was right, with so many Republican elected officials in Washington and across the country endorsing him since South Carolina voted on Feb. 20.

But, how to attack Trump?

Rubio is offering policy contrasts with the front-runner, notably on health care and foreign policy. But the thrust of his jabs have centered on Trump's character and business dealings. The Rubio campaign decided that trying to label the New Yorker a con man and a fraud would be more effective than critiquing his liberal past and ideological malleability. The independent super PAC supporting Rubio, Conservative Solutions PAC, is driving this message in new television spots and other advertising.

"Trump's appeal is not ideological, it's his attitude of being a winner that he projects. To stop him you have to chip away at that — because he's not," a source close to the campaign said.