But a funny thing happened on the way to Mitt Romney’s hoped-for coronation as King of the Indies, the man who can lure the all-important swing voters from Obama.

Independent voters don’t like Romney much, either. In one of the more surprising developments this season, the GOP front-runner — who is expected to win handily in Tuesday’s primary — is sinking, Obama-style, with the unaffiliated third of the national electorate that likely will determine both candidates’ fates in November…

Adds Suffolk University poll director David Paleologos: “Obama is so vulnerable with independents, given the economy and health care. But it’s not at all clear that Romney can do any better with them at this point. … That’s why Tuesday’s going to be so interesting.”

The primary provides the former Massachusetts governor with a critical test of his support among middle-class swing voters after a disappointing performance among independents in Iowa, and a string of gaffes (“I like being able to fire people who provide services to me”) that undercut his claim to be their economic champion.