Republican Walter Jones, a North Carolina conservative, said on ABC's This Week on Sunday that he would offer legislation this week setting a timetable for the US withdrawal from Iraq.
"I voted for the resolution to commit the troops, and I feel that we've done about as much as we can do," said Jones, who coined the phrase "freedom fries" to lash out at the French for opposing the Iraq invasion.
Other Republicans on television talk shows joined Democrats in criticising the administration for playing down the insurgency, while overestimating the ability of Iraq's fledgling forces to fight without US soldiers in the lead, and failing to plan for the post-invasion occupation.
But the White House on Monday rejected calls for setting a precise timetable, even as a new poll showed almost six in 10 Americans want at least a partial pullout of US forces.
White House response
"We will leave when we complete the mission," White House spokesman Scott McClellan said.
"We are not going to stay a day longer than what is necessary. But what we're working to achieve in Iraq is vital to peace and security for generations to come," he said.
Republican congressmen say US
public support is slipping away
On Sunday Senator Lindsey Graham, a South Carolina Republican, said on CBS' Face the Nation: "The insurgency is alive and well. We underestimated the viability of the insurgency."
He said the administration has "been slow to adjust when it comes to troop strength and supporting our troops".
Graham said the army was contending with a serious shortfall in recruiting "because this war is going sour in terms of word of mouth from parents and grandparents".
He said "if we don't adjust, public opinion is going to keep slipping away".
Jones, a member of the House of Representatives Armed Services Committee, said "primarily the neoconservatives" in the administration were to blame for flawed war planning.
"The reason of going in for weapons of mass destruction, the ability of the Iraqis to make a nuclear weapon, that's all been proven that it was never there," he said.
Jones joins some of Congress' most liberal Democrats in demanding a deadline to withdraw troops from a conflict they said had been too costly in US lives and money.
According to a new Gallup Poll, nearly six in 10 Americans say the United States should withdraw some or all of its troops from Iraq, up from 49% who held that view in February, USA Today reported in its Monday edition.
The Bush administration contends that setting a withdrawal date would fuel an insurgency that Vice President Dick Cheney recently said was in "the last throes".
"If the insurgents drive us out ... we've lost a big battle in the war on terror"
Senator Lindsey Graham,
South Carolina Republican
Graham opposed setting a date. "If the insurgents drive us out ... we've lost a big battle in the war on terror," he said.
Jones said he was pushing the legislation because his "heart aches" at the about 1700 US soldiers killed and 12,000 seriously wounded in Iraq. He said Iraqis should defend themselves once their forces were trained.
Call for candour
Curt Weldon, a Pennsylvania Republican who just returned from Iraq, joined several Democrats saying the administration had to be more candid and acknowledge that it could take about two years to train Iraqi forces to replace US soldiers and allow a significant pullout.
"We can't come back to America and have our people being convinced that the Iraqi troops are prepared to take over, when they're not," he said on NBC's Meet the Press.
Weldon also said the administration had to "come to grips" with a rising insurgency, boosted by fighters from Syria and Iran, "which for some reason our intelligence community does not want to acknowledge or deal with".
Weldon said he heard "a common theme" in Iraq that the largest number of foreign insurgents might be coming from Syria but that "Iran overwhelmingly has the quality behind the insurgency".
Senator Chuck Hagel, a Nebraska Republican, said on CNN's Late Edition that "many of us warned this administration before we ever put a boot on the ground" that it would face a long-term conflict. "We didn't have plans for it. And we are now where we are," he said.