A House Republican who spent almost three decades in the Army suggested Sunday that Donald Trump is unfit to be commander-in-chief.

"I have concerns about giving that guy an army," Rep. Chris Gibson, R-N.Y., said in a appearance on a radio program in New York.

"As someone who has served for 29 years, I mean, I have concerns given what I have heard to date about his temperament and the judgement he has," Gibson said.

Trump critics, including Sen. Marco Rubio, R-Fla., who is battling the businessman for the Republican presidential nomination, have raised similar concerns. But Gibson's status as a combat veteran gives his attack added sting.

Gibson is a retired Army colonel who served four tours in Iraq. His decorations include a Purple Heart.

Gibson won re-election easily in 2014 in an upstate New York district split closely between Republicans and Democrats.

He announced early this year that he will resign from Congress after completing his current term in 2016. Gibson, who is honoring a pledge to term limit himself, is preparing to launch a New York gubernatorial bid.

Despite his concerns about Trump, Gibson would not rule out backing the billionaire if he wins the Republican presidential nomination.

"He is running for president of the United States under the party that I'm in," the congressman said on "Effective Radio with Bill Samuels" on 970 AM in New York. "I'm prayerful that we will see some kind of evolution in that guy."

Gibson, a moderate by national standards who supports efforts to curb climate change, said Trump is exploiting "alienation in the Republican party" driven in part by anger at GOP congressional leaders.