Colin Powell’s endorsement of Obama = hardest-hitting cross-party endorsement ever?

[Redban]

We’ve seen other cross-party endorsements, where a Republican endorsed a Democrat or a Democrat endorsed a Republican.  For example, John Kasich endorsed Biden and spoke at the 2020 DNC. Michael Steele endorsed Biden. Colin Powell endorsed Obama 2012 and Hillary in 2016

But in 2008, was Powell’s endorsement of Obama the one cross-party endorsement that had the most sting?

Kasich and Steele had already disconnected with the Republican Party when they endorsed Biden. Powell’s 2012 and 2016 endorsements didn’t have the same sting because people already expected that he would endorse Obama / Hillary

But in 2008 - he was not that far removed from the Bush administration, which was still running the White House, his endorsement was a total surprise, and he and McCain were reportedly friends.

Was this the most biting cross-party endorsement, or were there others from the past?

[OSR stands with Israel]

Powell had a pretty big falling out with Bush and the Neocons and as early as 2005 had expressed regrets for that UN Speech:

https://www.abc.net.au/news/2005-09-09/powell-regrets-un-speech-on-iraq-wmds/2099674


McCain by 2008 was running on a platform that was even more neoconservative than Bush's so its not a surprise that Powell endorsed Obama .

[Sumner 1868]

It was definitely unusual, but I don't think it had much impact. It just highlighted how doomed McCain was.

[Landslide Lyndon]

Powell's endorsement didn't move any votes but was good for a few favorable media cycles.
It was also an early indicator of moderate Republicans being repelled by the crazies who were taking over the GOP. According to "Game Change" the hate-soaked rallies were people were calling Obama an "Arab" and a "terrorist" were a big reason why Powell broke his neutrality and endorsed Obama.