Washington (CNN) -- President Barack Obama is expected to announce a plan that would result in the 30,000 U.S. "surge" forces being withdrawn completely from Afghanistan by the end of 2012, an administration official told CNN.

The president is expected to give a speech Wednesday on the Afghanistan troop drawdown.

The time frame would give commanders another two "fighting" seasons with the bulk of U.S. forces still available for combat operations.

An estimated 100,000 U.S. troops are serving in Afghanistan, some 30,000 of which are part of the so-called surge ordered in 2009 in a bid to control the rising violence.

Obama is mulling how many troops should be withdrawn this summer and by the end of the year.

He is expected to discuss preserving flexibility in force levels on the ground so commanders can adjust as conditions warrant, the official said.

The drawdown will be accomplished by troops returning home and not being replaced as well as canceling some proposed deployments.

White House press secretary Jay Carney told reporters Monday that Obama had yet to make a final decision on the size and scope of the troop withdrawal but would do so soon.

"The president is still in a process of finalizing his decision on the pace and scope of the drawdown that will begin in July of 2011," Carney said . "He's finalizing his decision. He's reviewing the options and the assessments and will have an announcement to make soon."

Obama has said troops would begin coming home in July, and he recently indicated the number would be significant.

(Source)