WASHINGTON — A former House lawmaker who is now co-chairman of the Iraq Study Group, Lee Hamilton, said yesterday that he’s “extremely doubtful” that Prime Minister al-Maliki will be able to secure the country and allow American forces to leave any time soon.

And in what has become a drumbeat from the region, yet another military commander said yesterday that it would be a mistake to draw down American troops just as the buildup is making its best progress.

“There is no chance that the Iraqi forces could take over at any time, or certainly by the first of the year,” Mr. Hamilton said in a nationally broadcast interview. “All of the support efforts, logistical and medical and so forth, they are not close to being able to meet,” Mr. Hamilton said.

Lieutenant General Graeme Lamb of the British army, the deputy commander of international forces in Iraq, said Iraqis also have a way to go to cleanse a police force infiltrated by Shiite militiamen. Officials have removed some 11,000 police suspected of sectarian bias, General Lamb told Pentagon reporters, but he added that the problem won’t be “solved overnight.”

Speaking earlier in an interview on NBC’s “Today Show,” Mr. Hamilton said Mr. Maliki’s government also has made little progress on needed legislation and other efforts at reconciliation.

“He’s had quite a bit of time now,” Mr. Hamilton said. “He’s known exactly what he’s had to do. He hasn’t done it. His rhetoric is pretty good. His performance is pretty bad.”

The former Democratic congressman from Indiana, long a major player in foreign affairs issues, was interviewed on the same day that Mr. Maliki told NBC News in an interview that he now believes Iraqi forces will be ready to secure the country on their own by the end of the year.

Speaking through a translator, Mr. Maliki said, “As soon as we reach this level of readiness, the door will be open for dialogue between us and Americans about our future plans. Now we are thinking as politicians about how to maintain robust long-term relations with the Americans whether they remain on Iraqi soil or pull out from Iraq.”

Mr. Hamilton’s comments also came at a time when, at home in America, unity within the Republican Party on Iraq is frayed, although holding up so far. Butmore pressure is being applied in this area as lawmakers from both the Republican and Democratic parties float proposals in the Senate to get American troops out of Iraq soon. General Lamb said that would be a mistake.

Troops are making “good progress, steady momentum” with the course set in January to escalate the number of troops and step up operations in Baghdad and surrounding militant strongholds. “I sense we’re on a fair course right now … it would be a shame to change it,” General Lamb said.

Democrats will try again this week to set a deadline for the reduction of American forces in Iraq.

On the GOP side, two moderate Republicans with respected foreign policy credentials have proposed their own hurry-up initiative, winning a polite but clear rejection from the White House.

President Bush’s national security adviser, Stephen Hadley, said “No” when asked Sunday whether Bush could live with the proposal by Senator Warner of Virginia and Senator Lugar of Indiana.

He said the administration’s “very orderly process” for reviewing its Iraq plans, keyed on a mid-September appraisal of progress, should be allowed to play out without preconditions.

“They’ve done a useful service in indicating the kinds of things that we should be thinking about,” Mr. Hadley said of the senators. “But the time to begin that process is September.”