(NBC NEWS) -- A tough confirmation process is underway for the president's pick for Secretary of Defense, former Nebraska Senator Chuck Hagel.
Hagel spent hours in the hot seat Thursday answering questions from the Senate Armed Services Committee about his controversial positions on the war in Iraq, sanctions against Iran, and his past comments about Israel.
Early on senators made it clear their examination of Hagel would not be quick or easy.
Hagel grappled with senators over whether he was wrong when he opposed the 2007 surge in Iraq.
"I'm not going to give you a yes or no. It's far more complicated than that," Hagel said when pressed on the matter by Senator John McCain.
Hagel's record as a senator caused frequent concern.
In 2001 he voted against sanctions on Iran to stop the country from obtaining nuclear weapons.
Hagel said he's now open to all options.
He defended his position on U.S. stockpiles of nuclear weapons.
He previously co-authored a report calling for cuts.
Hagel promised to support the rights of gays in the military and apologized for offensive comments he made accusing lobbyists for Israel of intimidating lawmakers.
If confirmed Hagel would be the lone Republican in President Obama's cabinet, and the first Vietnam veteran in the position.
His supporters argue that experience makes him uniquely qualified.
It's likely every Senate Democrat will support Hagel's confirmation.
So far he has the support of one Republican, and will need four more Republicans in his camp to prevent a filibuster.