Sources: McChrystal Wants Up to 40,000 More US Troops in Afghanistan

Congressional liberals who led the charge against the Iraq war are starting to turn their attention to Afghanistan, putting pressure on the Obama administration to scale back even as it prepares to consider a likely request to increase the U.S. troop presence.

Members of the "Out of Iraq" caucus are organizing into a new group whose mission will be to question the military surge in the country President Obama has deemed critical to the fight against terrorism.

"He will hear from us," said Rep. Lynn Woolsey, D-Calif., who was a founding member of the Iraq caucus.

"Afghanistan is not Iraq. The terrain is different. It's difficult. It's harsh. There's a question whether you could ever end all of your efforts successfully," said Rep. Sheila Jackson Lee, D-Texas, who is part of both groups.