Interesting:

CONCORD, N.H. -- Fred Thompson's one-time New Hampshire primary adviser, Dan Hughes, who for a time was identified as the campaign's state chairman, has resigned and thrown his support behind Arizona Sen. John McCain for president.

Hughes is now the vice chairman of the McCain New Hampshire operation. He showed up Tuesday with McCain for the official filing of paperwork to participate in the New Hampshire primary.

Hughes quit Thompson's team three days ago, and privately sources close to the Thompson campaign say the campaign had its differences with Hughes.

Hughes told FOX News that Thompson is not organizing in any way that indicates a serious candidacy and McCain is the "real deal."

Thompson was in Naples, Fla. Tuesday to offer his plan for reforming immigration policy.

Here's Hughes on his departure, speaking to the Concord Monitor:

"Nothing happened. That's why I left. If something happened, I'd still be there," Hughes said. "What they need me for if they weren't going to do anything?"

Hughes was the go-to guy for Thompson through the summer and last month, when Thompson became an official candidate. But Hughes has been disappointed with the showing from Thompson, who's come to New Hampshire just once as a candidate and once before he came.

"I don't want to be part of a campaign that's going to say 'Let's write off New Hampshire.' To me, that's sacrilege," Hughes said.

Hughes smelled a strategy that would forsake New Hampshire and focus on the South, where the former Tennessee senator and Law and Order star is seen as potentially strong.