From Vegas Insider last night:
Who could step in for Biden? If you believe the oddsmakers, Gavin Newsome is the top choice.
The Governor of California was listed as high as a 50/1 choice prior to the debate.
After Biden's downfall, Newsome is sitting anywhere between 8/1 and 12/1 odds, the latter being the consensus. As of Friday morning, less than 12 hours after the debate, Newsome has been moved to 5/1.
Along with Newsome, the betting markets suggest three other possible candidates to replace Biden. United States Vice President Kamala Harris is listed as 14/1 odds and so is Michelle Obama. Another big move from last night's debate was Gretchen Whitmer, the Democratic Governor of Michigan. Prior to the event, Whitmer was 100/1 and she's now sitting at 28/1 odds. Knowing Michigan is one of six "swing states" in the upcoming election, the narrative makes sense.