Vice President Kamala Harris has become the favorite to win November's presidential election according to several leading betting companies.

Betfair is offering odds of 20/21 (51.2 percent) on a Harris victory against 6/5 (45.5 percent) for Republican candidate Donald Trump.

This is a change from earlier odds where Trump had a 53 percent chance of winning versus 47 percent for Harris.

Harris became the Democratic Party's presumptive 2024 presidential nominee after President Joe Biden announced he was dropping out of the race and endorsed her on July 21.

Harris has polled ahead of Trump in more than a dozen opinion polls, though these measure the popular vote which may not determine the overall winner due to the Electoral College system.