Baghdad ? U.S. military commanders said Friday the troop buildup in Iraq must be maintained until at least next summer and they may need as long as two years to ensure parts of the country are stable.

The battlefield generals’ pleas for more time come in the face of growing impatience in the United States and a push on Capitol Hill to begin withdrawing U.S. troops as soon as this fall.

Maj. Gen. Rick Lynch, commander of the 3rd Infantry Division, said in an interview that if the buildup is reversed before next summer, the military will risk giving up the security gains it has achieved at a cost of hundreds of American lives over the past six months.

“It’s going to take through summer, into the fall, to defeat the extremists in my battle space, and it’s going to take me into next spring and summer to generate this sustained security presence,” said Lynch, who commands U.S. forces south of Baghdad.

U.S. forces are working to build the Iraq military’s ability to hold the gains made during the latest combat operations.

The White House said it still expects top commanders to deliver a report in September assessing the progress in Iraq, including whether the Iraqi government and its security forces have met 18 political and security benchmarks.

Pressure has reached a high level from both Republicans and Democrats in Congress for a change of course in the war – which is in its fifth year and has claimed the lives of more than 3,600 U.S. troops.

“There may be various generals or various politicians or others who want to mention some other key time, but I think the key time for the vast majority of my members is September,” Senate Republican leader Mitch McConnell, R-Ky., said Friday. “And it certainly is for me.”

In Washington, White House officials said the timetable for assessing progress in Iraq has not changed and that September remains the next critical time frame for judging the course of the war. President Bush, who met with veterans and military families, accused Democrats of delaying action on money to upgrade equipment and give troops a pay raise.

However, the legislation is not an appropriations bill that feeds military spending accounts but a measure used by Congress to influence the management of major defense programs, set goals and guide the 2008 military spending bill. It is needed to authorize military pay raises, although Congress typically does not finish the bill before fall and then makes pay raises retroactive.

A military analyst said there is an obvious disconnect between a military focused on future success and politicians gripped by past failures.

“The Army generals in Iraq believe that it is only now that they are implementing the right strategy for securing the country, so they deserve more time to do the job right, despite the four years of failure,” said Loren Thompson of the Virginia-based Lexington Institute.

Commanders have said they fully expect to provide the September report, but it may take much longer to determine whether the improvements are holding and the country is becoming stable.