WASHINGTON (CNN) -- Sen. Barack Obama called President Bush's plan to increase troop levels a "tried and failed policy" during a speech on the Senate floor Thursday and said he planned to introduce legislation to cap U.S. troop levels in the war-torn country.

"When it comes to the war in Iraq, the time for promises and assurances, for waiting and patience, is over," the Illinois Democrat and likely presidential candidate said. "Too many lives have been lost, too many billions have been spent for us to trust the president on another tried and failed policy opposed by generals and experts, opposed by Democrats and Republicans, opposed by Americans and even the Iraqis themselves."

Obama also recognized that two of his potential rivals for the Democratic presidential nomination have already introduced similar legislation capping U.S. troop levels in Iraq.

"I want to emphasize that I'm not unique in taking this approach, Obama said."I know that Senator Dodd has crafted similar legislation."

"Senator Clinton, I believe, yesterday indicated she shared similar views," he added.