US presidency on a knife-edge: What happens next?

Brad Maurer, of Harrisburg, holds a sign during a "Rally to Count Every Vote," on the Capitol steps in Harrisburg, Pa., on Wednesday. Picture: Sean Simmers/The Patriot-News via AP

Delays and potential legal battles are looming over the US presidential election, with the result still too close to call.

The contest between Donald Trump and Joe Biden may remain on a knife-edge for days, with both men still in with a chance of winning enough Electoral College votes from the undeclared states to secure the presidency.