WASHINGTON — Critical to U.S. plans for redeploying American troops from the battlefield, Iraq’s security forces appear far from ready to take over the fight against al-Qaida and insurgents, an independent report concluded.

Retired Marine Corps Gen. James Jones, who led the 20-member panel studying Iraqi security forces, was to testify before Congress today. His report, a copy of which was obtained by The Associated Press, said the Iraq’s security forces would be unable to take control of their country in the next 18 months.

The readiness of Iraq’s security forces will be an important element in the congressional debate over the war. Republicans see success by the Iraqi forces as key to bringing U.S. troops home, while an increasing number of Democrats say the U.S. should stop training and equipping such units altogether.

The study found that the Iraqi military, in particular its Army, shows the most promise of becoming a viable, independent security force with time. It predicted that an adequate logistics system to support these ground forces is at least two years away.

Worse off is the Iraq national police force. The study, which described the police force as dysfunctional, corrupt and infiltrated by militias, recommended that the force be scrapped and entirely rebuilt.

These units “have the potential to help reduce sectarian violence, but ultimately the (Iraq Security Force) will reflect the society from which they are drawn,” according to the report. “Political reconciliation is the key to ending sectarian violence in Iraq.”

The United States has spent $19.2 billion on developing Iraq’s forces and plans to spend another $5.5 billion next year. According to Jones’ study, the Iraqi military comprises more than 152,000 service members operating under the Ministry of Defense, while the Ministry of Interior oversees some 194,000 civilian security personnel, including police and border control.

The review is one of several studies that Congress commissioned in May, when it agreed to fund the war for several more months but demanded that the Bush administration and outside groups assess U.S. progress in the four-year war.

A senior Pentagon official said Wednesday that the U.S. military does not believe the Iraqi national police should be disbanded but acknowledges that getting the Iraqi army up to speed will take a while.

“We’ve always recognized that this was a long-term project,” Pentagon press secretary Geoff Morrell said.

Several lawmakers — many of whom face tough elections next year — said they would be unswayed by the Jones report and other independent assessments. Congress would fare better by finding a bipartisan solution that would bring troops home, they say.

“No matter what these reports suggest or what Congress infers from them, it is clear that it is time to develop a post-surge strategy,” 13 lawmakers, including three Republicans, wrote on Wednesday to House Speaker Nancy Pelosi, D-Calif., and Majority Leader Steny Hoyer, D-Md.

According to the study, the panel agreed with U.S. and Iraqi officials that the Iraqi Army is capable of taking over an increasing amount of day-to-day combat responsibilities, but that the military and police force still would be unable to take control and operate independently in such a short time frame.

“They are gaining size and strength, and will increasingly be capable of assuming greater responsibility for Iraq’s security,” the report states, adding that special forces in particular are “highly capable and extremely effective.”

The report is much more pessimistic about Baghdad’s police units. It describes them as fragile, ill-equipped and infiltrated by militia forces. And they are led by the Ministry of Interior, which is “a ministry in name only” that is “widely regarded as being dysfunctional and sectarian, and suffers from ineffective leadership.”

Accordingly, the study recommends disbanding the national police and starting over.

A group of liberal Democrats said Wednesday the U.S. should stop supporting these forces entirely and withdraw U.S. troops.

“How can we be sure we are not putting guns into the hands of a future enemy and empowering them for generations to come?” said Rep. Maxine Waters, D-Calif.

Other Democrats say party leaders have set their sights on the $147 billion President Bush requested for the war as a means of forcing a drawdown of U.S. forces.

Rep. James Moran, D-Va., a member of the House panel that oversees the military budget, said an option being considered is a bill that funds the troops, but in three- or four-month installments, and directs that the money be used only to bring them home.