The Bush administration, which accuses President Bashar Assad's government of supporting terrorism, has resisted calls for direct talks to help ease the crisis in Iraq and make progress in the Israel-Palestinian peace process.
Soon after Pelosi's arrival in Damascus, Bush criticized her visit.
"A lot of people have gone to see President Assad . . . and yet we haven't seen action. He hasn't responded," he told reporters at a Rose Garden news conference. "Sending delegations doesn't work. It's simply been counterproductive."
Pelosi, a California Democrat, did not comment on Bush's remarks before heading from the airport to Damascus's historic Old City. She was scheduled to meet Assad today.
Wearing a flowered head scarf and a black abaya robe, Pelosi visited the 8th-century Omayyad mosque, shaking hands with Syrian women inside and watching men in a religion class sitting cross-legged on the floor.
She also stopped at an elaborate tomb in the mosque, said in Muslim tradition to contain the head of John the Baptist, and made the sign of the cross.
About 10 percent of Syria's 18 million people are Christian , and John the Baptist is revered as a prophet by both Christians and Muslims.
At a nearby outdoor market, Syrians crowded around, offering her dried figs and nuts and chatting with her. She strolled past shops selling olive oil soaps, spices, and herbs, and at one point bought some coconut sweets and eyed jewelry and carpets.
Democrats have argued that the United States should engage its top rivals in the Mideast -- Iran and Syria -- to make headway in easing crises in Iraq, Lebanon, and the Israeli-Arab peace process. Last year, the bipartisan Iraq Study Group recommended talks with the two countries.
Bush rejected the recommendations. But in February, the United States joined a gathering of regional diplomats in Baghdad that included Iran and Syria for talks on Iraq.
Visiting neighboring Lebanon on Monday, Pelosi shrugged off White House criticism of her trip to Syria, noting that Republican lawmakers met Assad on Sunday without comment from the Bush administration.
"I think that it was an excellent idea for them to go," she said. "And I think it's an excellent idea for us to go as well."
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