Will Republican leaders shift the Syria vote?

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Media captionSpeaker of the House John Boehner: "America will stand up when it is necessary"

The strong backing of senior Republican John Boehner must be a relief to the president.

Mr Boehner, usually a fierce critic of the president, is the leader of the Republican-controlled House of Representatives, where so many of Mr Obama's plans have met their death.

Another leading politician who often has harsh words for the president, Senator John McCain, appears to be on board too, although he says he needs more clarification before he puts himself in the "yes" camp.

They may persuade some of their colleagues, but the real importance of their change of heart is the indication of mainstream Republican thinking.

I'm up on Capitol Hill at the moment. Many are still listening to the arguments, keeping their council on how they will vote.

But it is more than possible that however much they dislike the president, they do not want to leave their country in a position where so many have already argued it would be weakened in the eyes of the world.