Gay marriage tangle for White House – live US political coverage

 Arne Duncan follows Joe Biden in support of gay marriage
• White House refuses to comment on change in policy
• Romney silent as supporter accuses Obama of treason
• CIA foils new underwear bomb plot in Yemen

US vice-president Joe Biden said at the weekend he was 'absolutely comfortable' with same-sex unions. Photograph: Lucas Jackson/Reuters

5pm: More on the Yemen bomb plot – the White House spokeswoman says President Obama learned about the plot in April and was assured the device posed no threat to the public:

The president thanks all intelligence and counterterrorism professionals involved for their outstanding work and for serving with the extraordinary skill and commitment that their enormous responsibilities demand.

4.20pm: This just in – a scoop by the Associated Press:

The Associated Press has learned the CIA thwarted a plot by al-Qaida's affiliate in Yemen to destroy a US-bound airliner using a bomb with a new design around the one-year anniversary of the killing of Osama bin Laden.

US officials say the plot involved an upgrade of the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas 2009. This new bomb was also built to be used in a passenger's underwear but contained a more refined detonation system.

The would-be suicide bomber was told to buy a ticket on the airliner of his choosing and decide the timing of the attack. It's not immediately clear what happened to the would-be bomber.

4.09pm: BuzzFeed Politics has an interesting find in Mitt Romney's tax return: he has paid $2m in foreign taxes since 2000:

At a town hall here today, Mitt Romney was confronted by a questioner about foreign taxes he reported on his income tax returns, a charge Mitt Romney appeared to deny.

"I don't think I paid any foreign income taxes, but I'll look at it," Romney replied over the boos of the audience for the hostile questioner.

But in fact, Romney has paid over $1.2 million in foreign taxes for "passive category income" since 2000, according to his 2010 income tax return.

Additionally he has paid over $800,000 in foreign taxes for "general category income" according to the same filing.

3.46pm: Reading through the transcript of today's White House briefing, press secretary Jay Carney was given an unusually hard time by the usually supine press corp over the issue of gay marriage. For example:

Question: I think there are very few people who think that the president is not going to, after November, whether he's re-elected or not, come out in favor of same-sex marriage. I think there are very few people on the president's campaign who doubt that; very few people who support the president, very few people who oppose the president who have any doubt that that is what is going to likely happen.

And if that is the likely future of the president and his position, given that you don't have any news to drop on it, but probably his mind has been made up, why not just come out and say it and let voters decide? It seems cynical to hide this prior to the election.

Jay Carney: I think the president's position is well known. He's spoken to this. It's gotten a great deal of coverage. I don't have an update to provide you on the president's position.

Followed by:

Question: Is the president comfortable with the fact of men marrying men and women marrying women?

Carney: The president is comfortable with same-sex couples, as the vice president said, being entitled to the same rights and the civil rights and civil liberties as other Americans.

And this:

Question: Let me ask you this. You have a number of Democratic governors throughout this country – Governor O'Malley, Governor Cuomo, Governor Malloy, to name a few, now the vice president – who all support same-sex marriage. Why doesn't President Obama support same-sex marriage?

Carney: I just don't have an update for you on the president's position.

"I don't have an update for you" is the new "no comment".

3.10pm: Safely away from the crowd at his Ohio event, Mitt Romney is quizzed by journalists about the audience member's charge of treason at the president. Romney told CNN:

I don't correct all of the questions that get asked of me. Obviously I don't agree that he should be tried.

Romney said much the same to the New York Times and Washignton Post when they asked if he agreed that Obama should be tried for treason: "No, of course not."