You can’t run a war from Capitol Hill. Congress’s thoughts of choking off President Bush’s military “surge” in Iraq are dissolving just as they needed to take on substance. That is for good constitutional reasons, as well as fear of the impact on the 2008 elections. But even though Congress has blinked first in the scuffling with the White House, the row may have curbed the President’s planning on Iran.

Since the Democrats took control of both houses of Congress in November, on the back of public fear about the course of the Iraq war, they have been struggling to work out what their own policy on the conflict should be. At least, when Bush announced the surge earlier this year, they had a target.

But not tactics for attacking it. The first plan, and the most obvious, was to cut off funding, as Congress did over Vietnam. Under the Constitution, that is the most direct way that Congress can interfere with the President’s conduct of a war, once started. Robert Gates, Secretary of Defence, and Condoleezza Rice, Secretary of State, last week asked Congress for an extra $235 billion for Iraq and Afghanistan, on top of the $350 billion already spent (and on top of the $500 billion a year in “regular” defence spending).

But disarray among Democrats has made that attack inaccessible. “We don’t have the votes to do it,” Representative John Murtha, one of the loudest voices for pulling the troops out now, said on Sunday. “And the public, they don’t want that to happen. They want the troops to be entirely funded.”

That is the core of the Democrats’ problem. Public dismay at the war is still rising, but that is not the same as a desire to see the troops put in danger, the interpretation that many appear to put on a cap on the funds. That route having failed, congressional Democrats are also considering trying to insert curbs on the mission itself into the spending bill.

Some are direct, such as limiting the time that troops could be there, while others are oblique, such as specifying that soldiers must have a period at home before their next tour in a conflict zone, a rule that could force withdrawal on an overstretched Army.

Here Democrats are on shakier constitutional ground. Congress has no right to tell the President how to fight a war. In theory, this is a clash that could go to the Supreme Court; in practice, that is almost inconceivable. This Congress does not have the public backing to take on the President on this issue. In any case, with an eye on 2008, Democrats do not want their fingerprints on any part of the management of Iraq.

But their opposition lets the White House know that Congress would be much more leery of authorising force — or funding in the future than it was over Iraq. That must have a bearing on the White House’s plans for Iran.

One day in Iraq

— Nouri al-Maliki, the Prime Minister, complained to the British Ambassador that a raid by coaliton troops and Iraqi special forces on an intelligence HQ in Basra violated Iraqi sovereignty because local officials were not notified.

— The British military said that it had acted quickly on a tip that detainees were being tortured

— A car bomb ripped through the oldest book market in Baghdad, killing 30 people, setting shops ablaze and leaving body parts scattered on a road

— US forces arrested Hussein al-Asati, a leading figure in al-Mahdi Army Shia militia, and three of his aides in the Shaab district of Baghdad

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