Gidget to play Mary Todd??

Wow! MRS. Lincoln!

Sally Field was officially in Washington on Tuesday for the Vital Voices gala – and unofficially to research her role as Mary Todd Lincoln.

Surprised? We were, too. Back in 2007, the Oscar-winning actress was rumored for the plum role in Steven Spielberg’s upcoming movie about Abraham Lincoln – but not a peep about it since then, not even when DreamWorks announced last year that Daniel Day-Lewis would play the title role.

But Field confirmed it Tuesday when she visited Ford’s Theatre. We learned that the actress took a private tour of the theater and museum with Director Paul Tetreault and Sarah Jencks, an expert on Mary Todd Lincoln, to better understand the former first lady.

The studio acknowledged the casting choice to us Wednesday. “I’m excited to be working with Sally for the first time,” Spielberg said in a statement. “I’ve admired her films, and she has always been my first choice to portray all the fragility and complexity that was Mary Todd Lincoln.”

At 64, Field is two decades older than Mary when she lived in the White House. But the two women share the same height (5-foot-2), girlish charm and nervous energy. And, you know, people looked a lot older back then.

“To play one of the most complicated and colorful women in American history is simply as good as it gets,” Field said in a statement also released by the studio.

She spent about an hour at Ford’s trying to get a sense of Mary’s day-to-day life, carefully examining her dishes and a blue fan she owned.

“She was absolutely riveted by that,” Tetreault said. But the actress declined a chance to look at an exhibit about the assassination.”

The long-delayed project, based on historian Doris Kearns Goodwin’s best-selling “Team of Rivals,” is scheduled to start filming this fall, with a release date in late 2012.