Former U.S. President Donald Trump's vice presidential running mate, U.S. Senator J.D. Vance, was set to address the Republican National Convention on Wednesday in a speech that could illustrate how Trump's "Make America Great Again" movement may dominate the party for years to come.

Trump's Democratic opponent in the Nov. 5 election, U.S. President Joe Biden, tested positive for COVID-19 and is experiencing mild symptoms, the White House said the same day. Biden, 81, who was on a campaign visit to Las Vegas, is returning to Delaware and will work from home while isolating.

The illness was the latest twist in a campaign that was dramatically altered four days ago when Trump narrowly survived an attempt on his life at a political rally in Pennsylvania.