John Bolton to announce decision on possible 2016 presidential bid

May 9, 2015: Former United Nations Ambassador John Bolton speaks during tthe Freedom Summit in Greenville. (AP)

WASHINGTON – The field of Republican presidential contenders might be getting another underdog.

Former United Nations Ambassador John Bolton will announce Thursday whether he's getting in the race, said spokesman Garrett Marquis.

Bolton, 66, served on President George W. Bush's foreign policy team. A prominent advocate for the war in Iraq, he is widely considered a neoconservative who favors an aggressive U.S. footprint in the world.

He has talked almost exclusively about foreign policy while courting voters in early voting states such as New Hampshire and Iowa in recent months. Bolton has been a critic of GOP presidential contender Rand Paul, saying that while Republicans are stronger on foreign policy than Democrats, they should not turn to "isolationists," which he considers the Kentucky senator to be.

"You need someone who understands in his or her gut that the most important thing they do is protect the country," he said.

Bolton's decision comes as the Iraq war he favored has emerged as an issue in the GOP campaign.

Former Florida Gov. Jeb Bush, brother of the former president, said this week that he would have handled the Iraq invasion differently in hindsight, but wouldn't say what he would have done. Several other GOP White House prospects, Paul among them, said they would not have authorized the invasion.