WASHINGTON (Reuters) - Afghan President Hamid Karzai is an "unworthy partner" who does not deserve a big boost either in U.S. troops or civilian aid, U.S. House of Representatives Speaker Nancy Pelosi said.

Pelosi, a skeptic on sending more troops to Afghanistan, also said in an interview with National Public Radio aired on Friday that there was not strong support among her fellow Democrats in Congress for "any big ramp-up of troops" to oppose resurgent Taliban forces.

She told NPR she had asked fellow Democrats to give President Barack Obama room to decide his Afghan strategy, which is expected to be announced in the coming weeks. Once Obama, also a Democrat, announces his decision, lawmakers would "not be shy" about responding, she said.

"The president of Afghanistan has proven to be an unworthy partner. We cannot fund a mission where we don't have a reliable partner and where whatever civilian investments we want to make, which are so necessary, will be diverted for a corrupt purpose," Pelosi told NPR News' Morning Edition.

"How can we ask the American people to pay a big price in lives and limbs and also in dollars if we don't have a connection to a reliable partner?"

Pelosi's comments came a day after Karzai was sworn in for his second five-year term. He has faced tough pressure from Western leaders to clamp down on widespread corruption and replace former guerrilla leaders and cronies with able technocrats in his new government.

In his inauguration speech, Karzai said he wanted Afghan forces to take the lead from foreign forces in securing the whole country in five years. There are about 110,000 foreign troops, including 68,000 U.S. soldiers, in Afghanistan.

Obama is weighing whether to send up to 40,000 more U.S. troops that his top commander in Afghanistan, Army General Stanley McChrystal, says is needed to quell the strengthening insurgency.

Recently the number of war critics in the U.S. Congress has grown. A troop increase by the president could make Democratic lawmakers nervous ahead of next year's congressional elections.

Democratic Senator Arlen Specter said an exit strategy was needed. "We ought not to add troops to Afghanistan, I even question staying there, unless it is indispensable to our fight against al-Qaeda," he said in remarks reported by "The Cable," a daily newsletter from Foreign Policy magazine.

"I, myself, believe that there's not strong support on the Democratic side in the Congress for any big ramp-up of troops going into Afghanistan, and I think that's a reflection of their constituents," Pelosi told NPR.

Congress appropriates funding for military campaigns. But the controversial Iraq war has demonstrated that many lawmakers are reluctant to cut off money for U.S. troops even for a conflict they dislike.

(Reporting by Susan Cornwell, editing by Vicki Allen)