Minnesota Congresswoman Michele Bachmann, one of Mitt Romney's most vehement critics, endorsed the presumed Republican nominee, four months after dropping out of the presidential race.

We've had a hard fought battle already to choose a candidate, Bachmann said, according to Fox News. This is the last chance we have to keep America from going 'forward,' over the cliff, as Governor Romney said, and restore the values of prosperity and freedom. Forward is the Obama campaign's 2012 mantra.

She tweeted her support as an official press conference in Portsmouth, Virgina was underway:

The endorsement is a big move for Bachmann, a three-term congresswoman who repeatedly dug at Romney during her campaign for providing what she said was the blueprint for Obama's health care reform while he was governor of Massachusetts. She repeatedly asked Republicans to vote for the true conservative -- a direct attack on Romney.

Just before she dropped out of the race, she told reporters, Mitt Romney is the chief author and the creator, the only governor in the history of the United States, to create a socialized medicine program for his state, called Romneycare. She also had told ABC, He can not beat Obama .. it's not going to happen.

But her role as a Tea Party leader and favorite among evangelicals could help the former Massachusetts governor win over the most conservative Republicans, who haven't quite warmed up to him.

Bachmann dropped out of the race after placing sixth in Iowa's Republican caucuses, while her poll ratings were in the single digits. Rick Santorum, another social conservative who dropped out of the race three weeks ago, has yet to officially back Romney.