George Bush's public approval ratings hit a new low yesterday as Democratic opposition to his planned US troop increase for Iraq rapidly gained momentum. Even before Mr Bush formally announces a fresh Iraq strategy tonight, Democrats in the new Congress discussed a range of options that include withholding funding for what they call an escalation of the war.

A poll in USA Today showed that approval for Mr Bush's handling of the war has dropped to 26%, a record low. About 61% opposed Mr Bush's proposed 20,000 increase in the number of troops.

As part of a push to sell the new plan, Mr Bush met Democratic congressmen at the White House yesterday. But the mood within the Democratic party, which only a few months ago was tentative in expressing opposition to the war, was hardening against the plan.

The White House sought to portray any block on funding as unpatriotic. Tony Snow, the White House spokesman, questioned whether the Democrats wanted to see Iraq succeed and whether they supported US troops. "We will have to see how it plays out," Mr Snow said.

Senator Edward Kennedy, one of the leading anti-war Democrats, promised yesterday to introduce a bill requiring Mr Bush to seek congressional approval for the billions he needs to send more troops.

Mr Kennedy said: "Congress has the power of the purse and what we are saying is before the president sends additional American troops into the civil war, the president has to come back to the Congress and get the authority for that deployment." He added: "We ought to take this step and stop the surge."

Senior Democrats from the House of Representatives and the Senate held a joint meeting yesterday to discuss tactics. Democrats are almost unanimous in opposition to the plan but divided on which steps to take.

Harry Reid, the Senate majority leader, said blocking funding was an option being discussed. The Democrats would "look at everything", short of cutting funds for troops already in the field, he said.

But Democrats are fearful of being labelled unpatriotic, even though such tactics were used in the latter stages of the Vietnam war and other conflicts over the past 50 years. Other options ranged from a resolution capping troop numbers to one simply describing the planned increase in numbers as a mistake.

The USA Today poll, which interviewed 1,004 people, found that almost half said the US could not achieve its goals in Iraq regardless of how many troops it sent. Eight in 10 said the war had gone worse than the Bush administration had anticipated and 72% said Mr Bush did not have a clear plan for Iraq. Worryingly for the Democrats, however, the poll showed that 66% had no confidence that the party had a clear plan for Iraq either.

Powerful committees in Congress will have their first chance tomorrow to question Condoleezza Rice, the secretary of state, and Robert Gates, Donald Rumsfeld's replacement as defence secretary, about the new plan.