Romney did a lot of smearing in '08, but I don't think it was against Palin. Mittens was dead and buried well before McLame was nominated and Palin was announced VP.
This Bachmann is Unfit thing wreaks of a Romney whisper campaign. He is the only one running that has a tendency towards ginning up this garbage.
Romney operatives have been suspected of sabotaging the McCain/Palin ticket, with an eye toward keeping Romney viable in 2012. Nothing ever proven, of course, but a lot of the "leaks" about the internals of the campaign, especially stuff about Palin, come from Romney loyalists.
Romney did a lot of smearing in ‘08, but I don’t think it was against Palin.
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It was the mittens campaign people who moved over to the McCain camp.
Pinging the guy I know with the most ready documentation of this.