Former Louisiana Gov. Bobby Jindal on Friday endorsed Republican presidential candidate Marco RubioMarco Antonio RubioOvernight Defense: Senate passes 0B defense bill | 3,000 US troops heading to Afghanistan | Two more Navy officials fired over ship collisions Senate passes 0B defense bill Trump bets base will stick with him on immigration MORE, the second former GOP presidential candidate to endorse him.

Jindal described Rubio as a "principled conservative" during an interview with Greta Van Susteren on Fox News's "On The Record," saying Rubio could "unify our party" and win in November.

His backing of Rubio comes amid debate over Rubio's conservative bona fides in the GOP race, after rival Ted Cruz won Monday’s Iowa caucus while Rubio placed third.

Jindal ended his own White House bid in mid-November after going hard after front-runner Donald Trump, who placed second in Iowa. 

Jindal on Friday praised Rubio over his national security views.

The endorsement comes just as Rubio seeks to maintain momentum heading into the New Hampshire primary Tuesday, where polls have indicated he's near the top of the GOP field.

Former Sen. Rick Santorum (R-Pa.) endorsed Rubio on Wednesday, the same day he suspended his White House campaign after taking 1 percent in the Iowa caucuses.


- Updated at 7:43 p.m.