Marco Rubio stumbled in New Hampshire 3 days after he got torn into at the GOP debate

Sen. Marco Rubio (R-Florida) was hoping to use his surprisingly strong third-place finish in the Iowa caucuses to leap ahead in New Hampshire.

That didn't happen.

Instead, Ohio Gov. John Kasich (R) surged to a projected second-placed finish in New Hampshire.

Rubio took the stage to address his supporters when, with about half of the vote in, he also narrowly trailed Sen. Ted Cruz (R-Texas) and former Florida Gov. Jeb Bush (R).

"Tonight, we did not wind up where we wanted to be, but that does not change where we're going to wind up at the end of this process," Rubio proclaimed, as his supporters cheered.

The senator also repeatedly proclaimed that he would ultimately win both the Republican nomination and the White House.

"We will win this election. We will win this election and we must win this election," he said. "We must win this election because if we don't win this election, we may lose our country. If we don't win this election. my children and yours will not inherit the greatest nation in the history of the world."

Rubio appeared to have momentum coming out of the Iowa caucuses, and polls showed him surging in New Hampshire. But several of his rivals - especially New Jersey Gov. Chris Christie (R) - viciously tore into him at last weekend's big GOP debate, possibly slowing him down.

Rubio made reference to his poor debate performance when addressing supporters.

"I did not do well on Saturday night," he said. "That will never happen again."