Of course there is nothing new in this question, and candidates have come to expect it. It was incessantly asked by journalists of Democratic party contenders seeking their party's nomination during the 2004, 2008 and 2012 presidential elections.

In fact it was the question in 2004 that launched the senate campaign of one Barack Obama. He clearly and vocally opposed the war.

Jeb Bush, the front-runner for the 2016 Republican presidential nomination (despite not officially declaring his bid), stumbled badly when he asked the question by Fox News. He first stated he would do what his brother, the former president George W Bush, did (invade Iraq). Then he equivocated, and fluctuated between "yes I would have", and then that his brother was mislead by bad intelligence, and consequently he would not have invaded.

Democratic contender Hillary Clinton, who voted for the war, tried to distance herself in the 2008 presidential nomination contest, but faced an authentic Iraq war opponent Barack Obama.