The White House on Wednesday was playing down a remark from Republican Sen. John McCain a day earlier in which he said the Bush administration had misled Americans into believing the Iraq war would be "some kind of day at the beach."

McCain, a longtime defender of the war, said he still does not believe it's wise for the U.S. to start withdrawing forces from Iraq, but the administration should have been more forthcoming about the challenges the military would face there.

"I think one of the biggest mistakes we made was underestimating the size of the task and the sacrifices that would be required," McCain said. "Stuff happens, mission accomplished, last throes, a few dead-enders. I'm just more familiar with those statements than anyone else because it grieves me so much that we had not told the American people how tough and difficult this task would be."

On Wednesday, a senior administration official said the White House did not underestimate the challenge that the coalition forces were going to face before they headed into the Mideast nation in March 2003.

"The president has made it clear from the beginning this fight would be tough, difficult and require sacrifice and he said on Monday these are not joyous times. But that to leave would be a mistake because the terrorists would follow us home," the official said.

McCain, R-Ariz., said rosy outlooks and other prognostications had undermined the American psyche, which had been led into thinking on several occasions that the end was near.

Those claims started on May 1, 2003, when President Bush boarded the USS Abraham Lincoln and stood below a banner proclaiming "Mission Accomplished" after the collapse of Saddam Hussein's regime. Vice President Dick Cheney said last year that the Iraqi insurgency was "in its final throes." The war has continued, with more than 2,600 members of the U.S. military killed.

That talk "has contributed enormously to the frustration that Americans feel today because they were led to believe this could be some kind of day at the beach, which many of us fully understood from the beginning would be a very, very difficult undertaking," McCain said.

White House press secretary Tony Snow noted that just weeks after the president's appearance aboard the aircraft carrier, the president said the war in Iraq and the War on Terror would be difficult. Two months later, he repeated it, and has continued to do so. On Monday, Bush said it again.

"This is ground that has been filed before. The president said it's difficult for us in America to see our soldiers who are being targeted, innocent women and children who are being murdered. It's difficult and the president has said from the beginning it has been difficult and that's not going to change for awhile," Snow said.

Snow added that Bush understands he is open to criticism, and criticism comes with tough decisions. But the president "is not interested in winning popularity polls."

Senate Democrats, meanwhile, said Tuesday that the best way to encourage Iraqis to get their political house in order is to begin a phased withdrawal from Iraq by the end of this year. Sen. Carl Levin of Michigan, top Democrat on the Armed Services Committee, said the longer the U.S. stays the course in Iraq, "the weaker we're going to be in the war on terrorism."

Minority Leader Harry Reid, D-Nev., said he was glad to hear McCain has realized "we need more than tough talk" on Iraq.

"It's time we win the War on Terror," said Reid. "To do that we must change the course in Iraq."

McCain told an audience at an appearance in suburban Cleveland on Monday that if U.S. troops announce a specific date to leave Iraq, insurgents will bide their time until they have an opportunity to act without interference.

"The chaos that would ensue would have direct implications for our national security," McCain said.

His remarks came while he was campaigning for Republican Sen. Mike DeWine, who faces a tough fight in his re-election bid against Democratic challenger Rep. Sherrod Brown.

DeWine said Congress would not have had the chance to authorize the war if the intelligence on Iraq's military capability and intentions were accurate.

"It would never have come up for a vote so it would have been an entirely different situation," he said.

FOX News' Anne Marie Riha and The Associated Press contributed to this report.