Which challenger did better with former supporters of the incumbent?

[Tekken_Guy]

Which challenger did better amongst people who voted for the incumbent president the previous election? Mitt Romney with Obama ‘08 voters or Joe Biden with Trump ‘16 voters?

[Shaula🏳️‍⚧️]

Romney with Obama 08' voters. Most of Biden's gains were with third party voters and non-voting suburban moderates.

[Motorcity]

I actually voted for "Biden in 20"

1. In 2008, Obama won 69.9 million and McCain got 59.9 million. Third parties got around 2 million votes.
58.2% turnout

2. In 2012, Obama won 65.9 million and Romney got 60.9 million. Third parties got around 2 million.
54.9% turnout

Looks like Romney only got about 1 million votes from Obama, but Obama's loss of voters were folks staying home

3. In 2016, Hillary got 65.8 million and Trump got 62.9 million. Third parties got around 7 million votes, much higher than usual.
55.7% turnout

Trump got around 2 million Obama voters. Hillary got around 1 million Romney voters.

4. In 2020, Biden got 81.2 million and Trump got 74.2 million. Third parties got about 2.2 million votes.
66.7% turnout

So, Biden got around 5 million third party voters who came to their senses in 2020. And an additional 11 million new voters. Trump got 12 million new voters. Biden's victory I believe came from the consolidation of the third party vote from 2016.