GREAT FALLS, Montana (Reuters) - Democrat Barack Obama squabbled with Republican John McCain on Friday over the number of U.S. troops in Iraq in the latest disagreement between the two likely presidential nominees over the unpopular war.

A U.S. soldier from Bravo Battery, 1-76 Field Artillery Battalion, looks through a pair of binoculars on the roof of a building at a fish hatchery in Hilla, about 100 km (60 miles) south of Baghdad, May 26, 2008. Democrat Barack Obama squabbled with Republican John McCain on Friday over the number of U.S. troops in Iraq in the latest disagreement between the two likely presidential nominees over the unpopular war. REUTERS/Erik de Castro

Obama criticized McCain, the presumptive Republican nominee, for giving an unrealistic view of how many American troops are in Iraq.

The five-year-old war, which is now broadly unpopular with the U.S. public, has become a fiery issue in the campaign for the November presidential election.

On Thursday, McCain said last year’s increase in the number of troops in Iraq was working. “I can look you in the eye and tell you it’s succeeding,” he said. “We have drawn down to pre-surge levels. Basra, Mosul and now Sadr city are quiet.”

Obama’s campaign was quick to say McCain was wrong.

“This is the guy who says I need more knowledge,” said Obama, a first-term senator from Illinois who has been criticized by McCain as too inexperienced -- particularly on foreign issues -- to be president.

“He’s wrong. That’s not true and anyone running for commander in chief should know better,” Obama said to a cheering crowd at a campaign rally. “As the saying goes, you’re entitled to your own view, but not your own facts.

The United States has 155,000 troops in Iraq -- about 20,000 more than before last year’s troop increase. The number would be cut to about 140,000 after current withdrawals are completed in July.

McCain’s campaign said it was just a question of tenses -- saying “drawn down” as opposed to “drawing down.” A campaign official said Obama’s campaign was just “nit-picking”.

Asked if he misspoke, McCain said in Milwaukee: “Of course not. I said we’ve drawn down. The rest of them will be home at the end of July.”

Obama accused the Arizona senator of refusing to admit his mistake.

“Well I don’t think tens of thousands of American troops amounts to nit-picking,” Obama said. “Tell that to the young men and women who are serving bravely and brilliantly under our flag.”

McCain is a former Vietnam prisoner of war who has been a prominent supporter of the decision to invade Iraq in 2003. He has vowed to keep U.S. troops there until the war is won.

Obama, who has moved within a few dozen delegates of beating rival Sen. Hillary Clinton of New York for the Democratic presidential nomination, was an early opponent of the war. He has promised to remove U.S. combat troops from Iraq within 16 months of taking office.

McCain has made eight trips to Iraq since the war began and says Obama needs to go there and talk to generals and troops on the ground. He has said Obama does not have the knowledge and experience to make judgments on the situation in Iraq and invited Obama to travel together to Iraq.

Obama dismissed the joint trip proposal as “nothing more than a political stunt.” He has been to Iraq once -- as part of a congressional delegation in 2006.

(Additional reporting by Tim Gaynor; editing by Mohammad Zargham)