The Washington Prowler has the story and the analysis:
Any doubts former Sen. Fred Thompson isn’t getting into the race have probably flown out the window based on the news this morning that Rep. Marsha Blackburn has jumped off the Mitt Romney Bandwagon and endorsed Thompson. Given that Blackburn is friends with Thompson and from the same state, the endorsement isn’t a surprise. But the timing is. Thompson isn’t announced yet. This leads us to believe that Blackburn must know something other folks don’t. Otherwise, why so publicly go out on a limb and embarrass the Romney camp? According to Romney insiders, Blackburn was slated to help run the "Women for Romney" operation and was in line to be a key national surrogate for the campaign down south. This isn’t a huge blow to that campaign by any stretch. But it is an interesting little twist to a race that is getting more interesting by the hour.