The US Senate will vote this week on whether to halt funding for the

The US Senate will vote this week on whether to halt funding for the
Iraq war by March 31 next year, in the latest twist of a bitter clash with the White House for control of the conflict.

Though the measure is deemed unlikely to pass the closely divided chamber, it will force senators to cast a highly visible vote for or against the war, and pile political heat on Republican backers of
President George W. Bush.

The Democratic-led Senate is also expected to vote this week on a second measure which would penalize the Iraqi government, including by reducing US troop numbers, if it failed to meet certain political and economic benchmarks.

But that move, the second of two amendments introduced to a water resources bill by Senate Majority leader Harry Reid (news, bio, voting record), heads off the threat of a veto by Bush by including a waiver mechanism he could use to block redeployments.

Senator Russell Feingold, co-sponsor with Reid of the first amendment, said the bill was a watershed moment for the Senate.

"The American people deserve to have the Senate go on record about whether or not it wants to end our misguided mission in Iraq and safely redeploy our brave troops," he said.

The move would prohibit funding for US troop deployments after March 31, 2008, except for targeted operations against terrorists, training Iraqi troops and protecting US military installations.

Bush earlier this month vetoed a 124 billion dollar war budget sent to him by Congress, as it included timetables for a troop withdrawal, forcing the House of Representatives and the Senate to frame new legislation.

Reid said that bringing up the two amendments would "ensure quick Senate passage" of legislation, so that it can be merged with a new war spending bill passed by the House last week and be sent to Bush.

Bush has vowed to wield another veto, if the House legislation is mirrored in the final legislation he is sent by Congress before it breaks up for a week-long recess in late May.

Reid has been discussing possible compromises with the White House over the last week, in a quest to find legislation palatable to Bush, which would fund US troops, but also placate anti-war Democrats.

Democratic leaders in the House have been so far unwilling to risk the political fallout by testing their power to cut off funding completely for US troops locked in fierce battle in Iraq.

In the Senate they lack the votes to force a similar bill through.

Increasingly, both Republicans and Democrats are looking to a pivotal period for Iraq policy in September, when General David Petraeus, commander of US troops in the country, is due to report on progress of Bush's strategy to deploy 28,000 more US soldiers to Iraq.

Bush wielded his veto for only the second time two weeks ago to strike down a joint Senate and House bill tying war funding to the timeline to start bringing home 146,000 troops in Iraq in October, from a war which has killed 3,395 of their comrades.

Bush's growing political vulnerability was underscored by news last week of a White House visit by 11 concerned Republican House members on Tuesday, which followed warnings by top Republicans that a "Plan B" might be needed if there is no clear success by September for the current US "surge" in Iraq.

Several senior Republicans have also warned that support for Bush's war policies could fray further without signs of substantial progress by September.