Nancy Pelosi, the Democratic speaker of the House, arrived in Damascus on Tuesday for a controversial visit that is seen as part of an attempt to sway US policy in the Middle East.
Pelosi, the third-highest ranking elected official in the US government behind the president and vice president, is the most senior US leader to visit the country since Syrian-US relations faltered in 2003.
The US has been trying to isolate Syria diplomatically since 2005. It has accused Syria of allowing militant fighters safe passage into Iraq and of meddling in Lebanese politics. The government in Damascus denies the charges.
Arab and Western leaders, as well as Democratic and some Republican lawmakers, have increasingly been calling on the Bush administration to open a dialogue with Syrian President Bashar Assad as a means of stabilizing Iraq and settling some of the wider region's may political crises.
US President George W. Bush criticized Pelosi's visit on Tuesday during a news conference at the White House.
He said that the visit sent "mixed signals" that "lead the Assad government to believe they are part of the mainstream of the international community, when in fact they are a state sponsor of terror; when in fact they are helping expedite or at least not stopping the movement of foreign fighters from Syria into Iraq; when in fact they have done little to nothing to rein in militant Hamas and Hezbollah; and when in fact they destabilize the Lebanese democracy."
Earlier, a White House spokesman described Pelosi's trip as a "bad idea."
During a brief visit to Lebanon Monday on her way to Damascus, Pelosi said that, on the contrary, it was "an excellent idea" for her and her high-level delegation of other politicians to visit Syria.
"When we go there, we'll be talking about the overarching issue of the fight against terrorism and the role that Syria can play to help or to hinder," Pelosi said.
She was greeted at Damascus airport by Syrian Foreign Minister Walid al-Moallem.
The complete schedule for Pelosi's visit has not been released. She quickly left the airport to visit the historic old city section of Damascus and was not expected to make any public appearances on Tuesday.
Pelosi and her delegation of other congressional representatives, including the Democrats Henry Waxman and Tom Lantos of California, Louise Slaughter of New York, Nick Rahall of West Virginia and Keith Ellison of Minnesota, as well as the Republican David Hobson of Ohio, were expected to dine at the American ambassador's residence on Tuesday night, where members of the Syrian parliament and opposition leaders will also be guests.
The last US ambassador was recalled in 2005 and the post is now vacant.
Pelosi was expected to meet Assad and other senior Syrian officials yesterday.
Before traveling to Damascus on Tuesday, Pelosi met Palestinian President Mahmoud Abbas at his headquarters in Ramallah in the West Bank.
After her visit to Syria, Pelosi is scheduled to travel to Saudi Arabia.