Marco RubioMarco RubioWar over the estate tax returns Clinton’s strategy: Get under Trump’s skin Rubio, Heck help out at car crash scene MORE on Friday argued the Republican Party will "split apart" if Donald TrumpDonald TrumpWhat will be October’s surprise? Poll: Half of Trump supporters don't trust integrity of election Report: German gov't thinks Trump would wreck US economy MORE wins the GOP nomination.
“He’s not going to be the nominee," Rubio told reporters before a rally in Oklahoma, while acknowledging Trump's status as the front-runner in the race.
"The Republican Parry would be split apart if he became the nominee, because we cannot allow the party of Reagan to be taken over by a con man," Rubio said.
Rubio has been portraying himself as the only alternative to Trump who can unite the fractured portions of the party and go on to win in November against the Democratic candidate.
Republicans acknowledged after the 2012 election that they would have to attract minority and female voters if they were to recapture the White House.
Rubio on Friday shied away from naming a state that he thinks he can win on Super Tuesday, when a 11 states, mostly in the South, hold Republican elections, as well as American Somoa.
Trump faced a barrage of attacks from Rubio and Cruz in the GOP debate on Thursday night, putting him on his heels before he responded Friday with an endorsement from Chris Christie.
Rubio continued to argue Friday that Trump is a "con man" who talks tough on illegal immigration while using foreign workers at his club in Florida.
“The time for action is now,” Rubio said, urging Republicans to get behind his campaign in an effort to stop Trump.