WASHINGTON  A new USA TODAY/Gallup Poll shows deepening pessimism on Iraq, even as many Americans are reluctant to limit money or troops for the war effort.

Only 28% say the United States will probably or definitely win the war, down from 35% in December and the lowest since the question was first asked in September 2005. The share of people who now call the war a mistake is 59% — the same as September 2005 and the highest level in the 58 times the question has been asked since the war began.

The poll asked about proposals circulating on Capitol Hill as Congress weighs how to exert influence on President Bush's Iraq policy. House Democrats could unveil their plans this week.

Six in 10 people said they want Congress to set a timetable to withdraw all U.S. troops by the end of 2008. Three-quarters said Congress should require that U.S. troops come home if Iraqi leaders don't keep pledges to reduce violence, and that U.S. troops have at least a year's stay in the USA between deployments to Iraq. The mandatory break is part of a plan by Rep. John Murtha, D-Pa.

At the same time, six in 10 people said they don't want Congress to deny funding for additional troops to be sent to Iraq. A slim majority, 52%, said they don't want lawmakers to revoke the authority they gave Bush in 2002 to use military force in Iraq.

Sen. Joseph Biden, D-Del., a presidential candidate and chairman of the Senate Foreign Relations Committee, is pushing to revoke that authority. Sen. Hillary Rodham Clinton, D-N.Y., another White House candidate, wants to cap troop levels in Iraq. That idea won support from 54% in the poll.

Linda Fowler, a government professor at Dartmouth College, said there's some recent evidence of a decline in violence in Baghdad, "but that doesn't seem to have penetrated the public consciousness."

Fowler said that is because of other developments such as "wrenching stories" about National Guard and Reserve troops going off on their second and third tours of duty, and the turmoil at Walter Reed Army Medical Center "reminding people that we are asking a great deal of our soldiers and not properly taking care of them."

Bush's approval rating in the new poll was 33%, while 63% disapproved of his performance. That was a slight dip from last month, when 37% approved and 59% disapproved.

The latest poll showed a partisan divide. Majorities of Democrats supported every step to limit or wind down the war. Majorities of Republicans supported only the year-long break for Guard and Reserve troops and withdrawing troops if Iraqi officials don't reduce violence.

Contributing: Kathy Kiely