Bush administration officials today clashed with senators over plans for a long-term US presence in Iraq after the current UN mandate expires at the end of this year.

Senators on the Foreign Relations Committee insisted that Congress should be allowed a vote on the draft strategic framework agreement, which allows the US to "conduct military operations in Iraq and to detain individuals when necessary for imperative reasons of security" without time limit.

Administration officials say that the agreement should be an executive one and have so far dismissed suggestions it must be ratified by Congress, raising the prospect of a fierce political battle in the run up to the election in November.

Though Ryan Crocker, the Ambassador to Iraq, assured senators earlier this week that the agreement would not establish permanent military bases inside Iraq, the absence of a timeframe has prompted concerns that the next president would be tied into a prolonged military engagement.

Both Democratic presidential candidates, Hillary Clinton and Barack Obama, plan to begin a phased withdrawal of troops from Iraq upon taking office and senators argued that the UN mandate should be extended for three months to allow for the change of administration.

A commitment to protect the Iraqi government against foreign or domestic aggressors is also a point of contention, with some senators suggesting it could force US troops to take sides in an internal ethnic conflict.

David Satterfield, the State Department’s Iraq Coordinator, found himself the target of both Democratic and Republican ire as senators insisted that they would not allow the Bush administration to ram through an agreement that would tie the hands of the next president.

Benjamin Cardin, a Democratic senator from Maryland, said it was "simply wrong" for such an agreement to be imposed "at the eleventh hour".

“There is a different view in Congress and among the majority of the American people to how the administration has proceeded in a strategic way in Iraq," he said. “There’s a belief that the president is trying to restrict the options of the next president and the next congress.”

Though John McCain, the presumptive Republican nominee, advocates a long term presence in Iraq, senators from the party held similar objections to their Democratic colleagues.

George Voinovich, a Republican senator from Ohio, said the agreement was "unacceptably binding".

“You are making commitments, and I have to say to you, and I’m saying to the administration now, you are not going to get this done,” he said. “It’s not going to happen and it’s going to turn into a big political thing between now and the election."

But Mr Satterfield insisted that the administration would not back down, saying it had the right to "pursue what it determines to be US national interests as well as the best means of pursuing those interests until the last day in office".

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