Obama to Send 34,000 Additional Troops to Afghanistan?

Obama is said to announce an additional 34,000 troops will be deployed to Afghanistan on December 1st. We have heard predictions before which have been wrong. Looks like they have come up with a new option. If Obama has stopped 'dithering' it should ease Karzai's concerns, at least somewhat. My main question is if Obama has already made the decision, why is he waiting until after Thanksgiving to make the announcement?

http://www.mcclatchydc.com/227/story/79380.html

"President Barack Obama met Monday evening with his national security team to finalize a plan to dispatch some 34,000 additional U.S. troops over the next year to what he's called "a war of necessity" in Afghanistan, U.S. officials told McClatchy.

Obama is expected to announce his long-awaited decision on Dec. 1, followed by meetings on Capitol Hill aimed at winning congressional support amid opposition by some Democrats who are worried about the strain on the U.S. Treasury and whether Afghanistan has become a quagmire, the officials said."