Marco Rubio is surging in New Hampshire - and he's narrowing the gap with Donald Trump

Sen. Marco Rubio (R-Florida) surged in a new poll after his better-than-expected third-place finish in the Monday-night Iowa caucuses.

A new CNN-WMUR New Hampshire poll published on Thursday found Rubio netting support from 18% of GOP voters there, up seven points from before the Iowa caucuses.

The results vaulted Rubio to second place. He trailed only front-runner Donald Trump, who captured 29% support in Thursday's poll.

The poll found Sen. Ted Cruz (R-Texas) in third with 13%, Ohio Gov. John Kasich (R) in fourth with 12%, and former Florida Gov. Jeb Bush (R) in fifth with 10%.

Rubio has also crept up on Trump in other New Hampshire and national polls.

Despite finishing third in Iowa, Rubio surprised by surpassing expectations for his performance in the state. The campaign reported being flooded with donations and rolled out several endorsements, including former Sen. Rick Santorum (R-Pennsylvania), who ended his own campaign Wednesday.

Following Rubio's finish in Iowa, several Republican rivals have stepped up their rhetorical attacks on the senator. 

New Jersey Gov. Chris Christie (R), whose poll numbers surged in the state last month, sunk to 4% support in Thursday's poll. He has been taking increasing aim at Rubio on the campaign trail.

"Marco Rubio hasn't accomplished one thing in his entire career. I mean, the fact is this is a guy who has only done one thing in the United States Senate - that was writing an amnesty bill for illegal immigrants and then to run away from it when the heat got turned up," Christie said in a Thursday "Morning Joe" interview..

Bush has also criticized Rubio, mocking the senator's speech following his third place finish.

The CNN/WMUR poll had a noticeably high, 6.8-point margin of error.