His one-day visit comes amid growing international concern over rising tensions in area.
Tens of thousands of tourists have also been stranded, as snow grounds flights.
But the independence-leaning opposition leader Tsai Ing-wen also vows to defend Taiwan's sovereignty.
The U.S. wants to see issues between the two dealt with peacefully, no matter who wins Saturday's polls.
Beijing didn't have regular diplomatic relations with pro-Western Seoul until the 1980s.
Chan is close to China's communist party and has called Taiwanese democracy "a joke."
The sale would mark the first time in four years that the United States has shipped arms to Taiwan.
The words "resignation" and "speech" are very similar in the Chinese phonetics system.
The two countries' leaders had met in November for the first time in more than 60 years.
China's Xi Jinping says independence proponents should not split the two sides.
Both presidents have an eye on Taiwan's elections as they prepare to meet in Singapore on Saturday.
The U.S.'s goal is to remind China and other countries about America's right to freely navigate the region.
The incident was captured on CCTV and has been released by the gallery.
More than 500 people were injured and one person was killed in the blaze.
Norway joins UK, Germany and others in signing up to China-led bank, with Japan and U.S. absent.
At least 31 people were killed when Flight GE235 lurched between buildings, clipping a taxi and overpass.
As many as 28 people appeared to have survived the crash after the plane crashed.
The U.S. State Department said it had not been notified in advance of the ceremony and that it was inconsistent with U.S. policy.
The quashing of pro-democracy protests in Hong Kong is souring China's relations with Taiwan
China fears the success of the Scottish Independence movement may inspire similar activism in its own restive regions
The report said that before the explosion, smoke with a "gas-like smell" was seen coming out of drains in the streets