Sen. John McCain (R-Ariz.) on Sunday stressed the president's decision to announce July 2011 as a tentative date to wind down combat operations in Afghanistan would deter allies from committing to the war effort.

The possibility that the United States could begin to transition power despite worsening conditions in Afghanistan, McCain hypothesized, could scare allies into providing fewer troops or dollars for the surge, out of fear they would be left to pick up where the U.S. military left off.

Such a drawdown could also galvanize regional extremism, added McCain, the ranking member of the Senate Armed Services Committee.

"You've got the watches, and we have the time. We dont want to say that...," McCain told NBC's "Meet the Press," noting he did ultimately agree with the president's decision to send more than 30,000 new troops to Afghanistan. "The rationale for war is to break the enemy's will."

"I'm saying we have to make a decision about what adjustments we need to make to win," he added. "If we're not successful with one strategy, we have to make adjustments to that strategy."

McCain has opposed the president's decision to announce July 2011 as a tentative transition date since the president announced it during a televised address on Tuesday. The senator even excoriated Secretary of Defense Robert Gates, in particular, when he and Secretary of State Hillary Clinton explained the White House's new Afghan strategy at a Senate Armed Services Committee hearing last week.

The Arizona senator repeated those objections on Sunday, adding the timetable approach could eventually convince the United States' 42 NATO partners, not to mention Pakistan, to commit increasingly less to the war effort. Ultimately, that could allow extremist groups to again gain a foothold in Afghanistan -- precisely what the Obama administration is trying to combat.

"We will be able to succeed," McCain said, noting success was even possibly by July 2011. "But I think they're on the defensive... and if we left, and allowed them to restore these safe havens without any threat," America's security and Afghanistan's stability could be compromised.