President Barack Obama's address Tuesday night will reveal "when he thinks we can begin to transition our forces out of Afghanistan," the White House's chief spokesman said Tuesday.

The administration had previously signaled such a discussion was likely, but only this morning did White House Press Secretary Robert Gibbs confirm the president would broach the subject of withdrawal.


Nevertheless, Obama's remarks are likely to frustrate congressional Republicans, many of whom have stressed since this weekend that any mention of withdrawal during Tuesday's speech would undermine the war effort.

"As the president said, we can't be there forever. This can't be nation building. This can't be open-ended," Press Secretary Robert Gibbs told CNN this morning.

"The president will discuss tonight the timeframe in which he believes we can transition our forces out of Afghanistan," added Gibbs.

Tuesday evening's speech at the U.S. Military Academy at West Point should prove most resonant for the president: Obama must convince skeptics on both sides of the political spectrum that his decision to deploy more than 34,000 troops is the correct call.

A number of left groups -- including and Code Pink -- have severely criticized the president for his decision to continue the conflict, and liberal filmmaker Michael Moore even sounded off at the president's call in a scathing Huffington Post op-ed published Monday.

Meanwhile, some Republicans have carped the president's strategy is not enough to accomplish the job, and others are hoping Obama will send the 40,000 troops Gen. Stanley McChrystal first requested. Still more, including Sen. Jon Kyl (R-Ariz.), warned the president not to speak of any timetable on Tuesday to ensure his new strategy's success.

"I really hope we can stay away from all this talk of an exit strategy," Sen. Jon Kyl (R-Ariz.) told "Fox News Sunday," later adding, "It tells the Taliban just to lay low until we leave."

Gibbs, however, said Tuesday morning that such a conversation was essential to convey to the White House's Afghan partners that they too must commit to the conflict to ensure its successful resolution.

"We have to help clear and hold areas that the Taliban control now, but we have to transfer that to a competent Afghan government that's addressed governance and corruption issues but also understand that they alone have the responsibility to provide their own security going forward," he said.