CLEVELAND, Ohio, (Reuters) – President George W. Bush on Tuesday brushed aside the criticism of fellow Republicans over Iraq and demanded the U.S. Congress allow his troop buildup more time to work.

Bush ruled out an immediate change in strategy, even though prominent Republican lawmakers like Indiana Sen. Richard Lugar have broken ranks and called for him to shift course on Iraq.

Defiant in the face of a frustrated American public and Congress, Bush said the 28,000 additional troops he ordered into Iraq have not been in place long enough to gauge results because the final wave arrived only last month.

The president defended his policy before the release as early as on Thursday of an interim report expected to show mixed progress by the Iraqi government in meeting U.S. security and political benchmarks. The report, due by Sunday, is bound to fuel further debate about the war. “We just started,” Bush told a business group in Cleveland. He asked Congress to wait for a report due in September from Gen. David Petraeus, the U.S. commander in Iraq, about the results of the troop increase. “I believe Congress ought to wait for Gen. Petraeus to come back and give his assessment of the strategy that he’s putting in place before they make any decisions,” he said. “That’s what the American people expect. They expect for military people to come back and tell us how the military operations are going,” Bush said.

Republican Sen. Olympia Snowe of Maine said impatience for a shift in policy continued to grow and that by September there could be enough support among Democrats and disaffected Republicans to pass a withdrawal timetable. “The tide has turned,” Snowe said.

In a sign of rising Republican pressure on Bush, Virginia Sen. John Warner, another Republican skeptical of Bush’s policy, told reporters he was working on a proposal about Iraq with Lugar that is in the “formative stages.” He declined to give specifics.

A new USA Today/Gallup poll showed that more than seven in 10 Americans favor withdrawing nearly all U.S troops from Iraq by April. Sixty-two percent said sending American troops to Iraq was a mistake, the first time that number has topped 60 percent in that poll.

White House officials had signaled Bush might emphasize that the troop increase was aimed at laying the groundwork for an eventual drawdown of U.S. troops from Iraq. But Bush made only a passing reference to that in his speech. “I believe we can be in a different position in a while,” he said. “But we couldn’t get there without additional troops.”

Several of Bush’s advisers have advocated trying to stem further Republican defections by holding out the prospect of an eventual troop drawdown, according to newspaper reports.

As Bush spoke in Ohio, White House national security adviser Stephen Hadley visited Capitol Hill to assure senators who support the troop increase that Bush was not going to pull back and would see it through at least until September.

Also on Capitol Hill, Vice President Dick Cheney met with Senate Republicans at their private, weekly lunch and held what some lawmakers described as a vigorous debate over Iraq.

Meanwhile, the White House threatened to veto the defense policy bill senators were debating, if it is amended to set a withdrawal date. The administration also threatened a veto over a provision the bill already contains — giving new rights to detainees at the military prison at Guantanamo Bay, Cuba.

Democratic leaders announced later that the House of Representatives will vote this week on a bill to change course in Iraq. The legislation would begin a phased withdrawal of U.S. combat troops within 120 days and their complete withdrawal by April 2008.