The math for Rubio is daunting. After getting thoroughly routed on Super Tuesday, Rubio is in so deep a delegate hole that he would now need to win roughly two-thirds of all the remaining delegates to guarantee his nomination ahead of Cleveland, according to a POLITICO analysis.

That is an enormously difficult, if not impossible, climb for a candidate who has so far won only a single state, Minnesota, and especially one who is not predicting victory in any of the next dozen states and territories that cast ballots, until his home state of Florida votes on March 15.

“It’s fair to say that Rubio’s path to 1,237 is shot,” Dave Wasserman, an analyst with the Cook Political Report who closely tracks the delegate race, said of the threshold to secure the nomination.

“There’s virtually no chance for Marco Rubio to get to a majority prior to the convention,” said John Yob, who served as a top delegate strategist for Rick Santorum in 2012 and John McCain in 2008.