June 23 (Bloomberg) -- Defense Secretary Donald Rumsfeld and top U.S. military commanders defended their handling of the war in Iraq today as Democrats and some Republicans in Congress sharpen criticism of President George W. Bush's strategy and polls show a decline in Americans' support for the conflict.

``Any who say that we've lost this war, or that we're losing this war, are wrong,'' Rumsfeld told the Senate Armed Services Committee in Washington. To set a timetable for withdrawing forces ``would throw a lifeline to terrorists who, in recent months have suffered significant losses'' and ``weakened popular support.''

Every day ``the new Iraqi government, with the help of the coalition, takes significant, positive steps down the road to freedom and to security,'' General Richard Myers, chairman of the Joint Chiefs of Staff, told the panel. ``We are on the right course, and we must stay that course.''

U.S. forces and Iraqi Prime Minister Ibrahim al-Jaafari have struggled to quell an insurgency that has killed more than 1,000 people since April 28. A CNN/USA Today poll released June 20 showed 59 percent of Americans want at least a partial withdrawal of the 135,000 U.S. troops there, and a New York Times/CBS poll said 51 percent of Americans think invading Iraq was a mistake.

The cost of the war in Iraq is ``$230 billion and rising'' and the administration's current strategy is ``unacceptable,'' Senator Carl Levin of Michigan, the ranking Democrat on the armed services panel, said.

Bush will meet with Al-Jaafari tomorrow at the White House, and on June 28 the president will give a major speech on the first anniversary of the U.S. handover of authority to an interim Iraqi administration.

Seeking Options

Democrats, and Republicans including Nebraska Senator Chuck Hagel and Arizona Senator John McCain, have stepped up criticism of the administration's strategy in Iraq and said alternatives should be considered.

Levin said Iraq should be told that the U.S. may pull out its troops unless the country meets a self-imposed deadline to adopt a constitution.

``The Iraqis have approved a timetable for adopting a constitution -- August 15 with the possibility of one and only one 6-month extension,'' Levin said. ``The U.S. needs to tell the Iraqis and the world that if that deadline is not met we will review our position with all options open including but not limited to setting a timetable for withdrawal.''

The Bush administration's pledge to keep U.S. troops in Iraq as long as needed lessens the chance that Iraqis will make necessary political compromises, Levin said. ``Only a political settlement will end the insurgency.''

Timetable `a Mistake'

Setting a timetable for withdrawal ``would be a mistake,'' Rumsfeld told the panel. He and Bush and other top officials in the administration say that would only embolden insurgents.

Rumsfeld said it's ``critically important'' that Iraq stick to its political timetable, but ``it's not for me to tell the Iraqi government what the president might do with regard to reviewing our situation.''

Massachusetts Democrat Ted Kennedy accused Rumsfeld of ``gross errors and mistakes'' in Iraq and said the U.S. now is in a ``seemingly intractable quagmire'' there -- a phrase recalling characterizations of the U.S. war in Vietnam. He asked Rumsfeld: ``Isn't it time for you to resign?''

`Not a Quagmire'

Rumsfeld said he has twice offered Bush his resignation and been denied, and he, Myers and General George Casey, commander of multinational forces in Iraq, each rejected Kennedy's assertion that the U.S. is bogged down in Iraq.

``There isn't a person at this table who agrees with you that we're in a quagmire and there's no end in sight,'' said Rumsfeld.

``It's clearly not a quagmire, never has been,'' Myers said.

To say the U.S. is mired in a guerilla war in Iraq is a ``misrepresentation of the facts,'' said Casey. ``It's an insurgency with no vision, no base, limited popular support.''

While the insurgency's strength is ``about the same'' as it was six months ago, there are more insurgents from other countries in Iraq now than there were then, General John Abizaid, commander of U.S. forces in the Middle East, said.

Syria is the main gateway for foreign fighters entering Iraq, Abizaid said. ``The key node is Damascus,'' he said.

Myers agreed. ``My worry is not just the border, it's the ease with which foreign fighters transit through'' and ``are facilitated.'' Syria's role is ``unacceptable,'' he said.

The Syrian government ``must have some knowledge of what's going on'' because ``it's a pretty tightly controlled country,'' said Myers.

20,000 Insurgents

U.S. and Iraq troops continue to fight an insurgency composed of four disparate groups which have honed increasingly sophisticated bombs, Lieutenant General John Vines, the No. 2 U.S. commander in Iraq, told a press conference June 21.

The insurgency includes as many as 20,000 people, the U.S. Defense Intelligence Agency director, Admiral Lowell Jacoby, told the Senate Armed Services Committee in March 17 testimony.

At least 20 people, including three Iraqi police officers, were killed today when a series of explosions struck a commercial area in central Baghdad as shopkeepers opened their businesses, Iraq's Interior Ministry said.

Fifty people were injured in ``multiple'' explosions, a ministry spokesman who declined to be identified said in a phone interview. Defense Ministry spokesman Salham Salah said there were five blasts that led to the officers' deaths, and that 10 civilians were hurt.

The blasts came about 12 hours after three bombs in a shopping area of the capital killed at least seven people and injured 55, the Interior Ministry said. The Associated Press, citing police, said the death toll in all of the attacks was 38.

`Last Throes'

Hagel said this week the administration has become ``disconnected from reality'' over Iraq. He cited comments by Vice President Dick Cheney that the insurgency is in its ``last throes.'' U.S. troops are ``losing'' in Iraq, Hagel told US News and World Report in an interview published June 19.

Asked by Levin whether the insurgency is, as Cheney had said, ``in its last throes,'' Abizaid declined to say.

In a speech June 21, Delaware Senator Joseph Biden, two days after he said he's running for president in 2008, said there's a ``credibility gap'' between Bush administration statements and the reality in Iraq.

To contact the reporter on this story: Jeff St.Onge in Washington at jstonge@bloomberg.net.

Last Updated: June 23, 2005 14:28 EDT