WASHINGTON — The architects of the current surge strategy for Iraq are worried the Republican Party may abandon the war in September and force President Bush to begin the withdrawal of troops from the country prematurely.

Both American Enterprise Institute scholar Frederick Kagan and a retired general, John Keane, the two men who persuaded Mr. Bush to launch the current counteroffensive in Iraq last December, said in interviews this week that they fear Republicans in Congress could be looking to declare victory and leave.

“The tragedy of these efforts is we are on the cusp of potentially being successful in the next year in a way that we have failed in the three-plus preceding years, but because of this political pressure, it looks like we intend to pull out the rug from underneath that potential success,” General Keane said yesterday.

The concerns are real. In the Senate there are anywhere from 10 to 15 Republicans who have signaled publicly and privately they could not support the current surge of troops come September, when Congress is set to vote on another temporary funding bill for the wars in Iraq and Afghanistan. At that time, General David Petraeus, the top American officer in Iraq, will give a status report on the current strategy. Those Republicans could create a veto-proof two-thirds majority in the Senate, assuming all Democrats vote for a hard withdrawal deadline or threaten to cut off funds.

Senator Lugar, the Indiana Republican and former chairman of the Senate Foreign Relations Committee, this week demanded a new strategy from the White House for Iraq. Meanwhile, the White House itself is quietly approaching disgruntled Republicans in the hope of coming up with a compromise Iraq solution for the fall.

Yesterday a spokesman for Senator McConnell, the Republican Senate minority leader from Kentucky who managed to keep all but two of his party’s senators from voting with Democrats to set a withdrawal deadline, said in an interview that the surge could not continue indefinitely. Don Stewart said, “The generals over there have said we will have fewer troops next year than we have, McConnell agrees with that assessment.”

That itself is a tricky matter. Another top American commander in Iraq, General Raymond Odierno, backtracked this week from remarks he had made last week that it was possible to start lowering the level of troops in Iraq by next spring. “What I said is if the Iraqi security forces continue to improve and we are successful, there’s a potential that we could withdraw by the spring,” General Odierno said on Sunday’s CNN “Late Edition.”

General Petraeus, who commands Multinational Forces Iraq, has explicitly lowered expectations in this regard, suggesting that the work of the surge will not be completed by September, that it may be too soon to make a judgment on the next strategy, and that he would need up to nine years to defeat the insurgency fully. One American officer familiar with early drafts of the assessments of the surge says that it will emphasize that Iraqi Security Forces are still at risk for infiltration, particularly if American soldiers withdraw.

For now, it appears that Republicans in Congress do not want to hear this sort of thing.

“People want to have some sense that this is not without end. Nixon beat McGovern because Nixon was leaving and McGovern wanted to surrender. Right now you have Bush saying we are not going to leave. If the president can stick the word ‘leaving’ into the strategy, he will be fine,” the president of Americans for Tax Reform, Grover Norquist, said Monday. “He cuts his problems in the Republican party in half, if people believe there will be fewer troops in six months than today.”

This is the kind of talk that worries Mr. Kagan and General Keane. “The most dangerous scenario is that the situation has improved enough that the Republicans insist on declaring victory and getting out,” Mr. Kagan said Monday. “And the problem is, the situation is very likely to be more stable and more secure, but not such that in September we could start withdrawing. If we did that, the situation will deteriorate again. ‘We almost fixed it, but whoops we let it go.’ That is not a good campaign platform.”

General Keane agrees. “All I know is what I have read in the newspaper and my own dialogue with the president. In that dialogue he is convincing that he intends to support the military commanders and he will back General Petraeus. Then you hear about all these other efforts, you wonder what is that all about, it flies in the face of what he tells the military commanders, it makes you wonder what is really going on,” he said.

Those efforts include the appointment of General Douglas Lute as the Bush administration’s “war tsar.” In his nomination hearing on June 7, General Lute said a “withdrawal ought to be considered.” Two Pentagon officials confirmed this week that Defense Secretary Gates in May ordered the armed services to begin drawing up contingency plans for a withdrawal from Iraq. The military draws up contingency plans for many scenarios and a senior military officer in Baghdad reached for this article warned not to read too much into that. But Mr. Gates himself has also started floating trial balloons on Iraq suggesting that a new strategy could have American soldiers retreat from Baghdad and focus on other parts of the country.

These signs suggest General Petraeus may be walking into a collision with the president who chose him to command the theater in Iraq in January. “We have been asked to bleed for this,” one American officer said on condition of anonymity. “And we think it’s a good cause. But we have no intention of being screwed over by this president.”

Mr. Kagan, who said he was still persuaded Mr. Bush supported the war, also warned that Mr. Bush could be choosing to assuage his party at the cost of his best general: “If the president, driven by his advisers or congressional confrere, try to find some way of defining victory down, well at some point he will have to make a decision about whether he is prepared to ignore the advice of the most talented commander who ever served under him.”