What makes you think he was popular with the Bushes?
He made GHWB's Presidency a partisan hell. Another poster says GW as Rangers' owner cast the dissenting vote to keep him from being Baseball Commissioner. I didn't remember that myself, but the poster was saying GW did that as payback for Mitchell's unrelenting partisanship against his dad. Also, a different poster has a quote from Mitchell totally badmouthing the Iraq War and saying the result is we must start withdrawing.
The Bushes are generally polite and personable, but I don't see how George Mitchell fits into their scene as President Bush's U.N. Ambassador.
The sad part is as I sit here and try to think of someone with the same smarts and gusto as Bolton, absolutely no one comes to mind. Smarts here, yes, and gusto there, yes, but not one individual who has both.
"I am yours to command, Master"
I didn't know that GWB is no friend of George Mitchell. I just know that the Bushes seem to cater to all kinds of Democrats in a bid to try to get them to say something nice about them. Never seems to work, does it? Maybe Mitchell then won't be the choice. I would imagine he would not want the pay cut involved either.