US election still too close to call: Clinton campaign chair

America's historic presidential election showdown between Donald Trump and Hillary Clinton is still too close to call, with several states still up in the air, the Democrat's campaign chair John Podesta said early Wednesday.

Trump appeared to be on the cusp of clinching the 270 electoral votes needed to win the White House, but Clinton still held onto a slim path to victory that hinged on her winning contests balanced on a knife's edge in Pennsylvania, Michigan and Wisconsin.

"They're still counting votes -- every vote should count. Several states are too close to call. So we're not going to have anything more to say tonight," Podesta said, indicating that Clinton would not be appearing in the coming hours.

Podesta said Clinton had "done an amazing job, and she is not done yet."