Four years ago George W. Bush was still proving himself.
"We will write not footnotes but chapters in the American story," he said at the 2000 Republican National Convention in Philadelphia.
He preached humility and had little tolerance for nation-building.
"If we're an arrogant nation, they'll resent us; if we're a humble nation, but strong, they'll welcome us," he said on the campaign trail in 2000.
But 9/11 changed everything.
Four years later, having proven his mettle in the ashes of the attacks, the challenge is different: then, he was trying to prove he was up to the job. Now, the president who took the war on terror to Iraq is trying to prove he got it right.
"America is safer with Saddam Hussein in a prison cell," said President Bush on the stump this week.
Former House speaker Newt Gingrich says any war president has a heavy burden.
"You've got to say, this is painful, this is hard, this is dangerous, and we have no choice," says Gingrich. "If the president wins that argument, I think he wins a very big election."
But critics argue the president did have choices in Iraq and that the pursuit of Saddam reflected an unwelcome change in America's 9/11 leader.
"After 9/11 it looked like strength and constancy," says Washington Post columnist E.J. Dionne. "During and after the Iraq war it looked like stubbornness and arrogance."
Brent Scowcroft, the national security adviser to President Bush's father, has renewed his doubts about the war in an interview with the New York Observer. He says this president has failed to reach beyond the mostly hard-line experts around him who were wrong about Saddam's weapons of mass destruction. And the Iraq war, he worries, has made it harder to confront nuclear nations like Iran.
Bush frequently says — "knowing what I know today, I would have taken the same action" — but now candidate Bush confronts a nation divided over war and his leadership on other issues as well.
Thursday he'll try to persuade the doubters he needs another four years to prove them wrong.