'I'm In': Braley Officially Announces Bid for Harkin's Senate Seat

Rep. Bruce Braley has announced he will seek to represent Iowa in the U.S. Senate in 2014.

The seat has long been held by Democrat Tom Harkin, who has announced he will not seek re-election.

Braley, a Democrat who currently represents Iowa's first district, sent out a Tweet Thursday morning with just two words: "I'm in," and a link to a Facebook image with the words, "Braley for Iowa."

"It's a big responsibility to represent the people of Iowa in the United States Senate, especially after Tom Harkin has shown us how for the last 30 years. But, if you are willing to help me, I'm ready to go," Braley wrote in an email to supporters.

To win the seat, he'll have to woo not just the Eastern Iowans who decisively re-elected him over Republican Ben Lange in November. He will also have to reach out to more conservative Western Iowa.

"Just as Sen Harkin did when he first ran, I'll need to meet a lot of Iowans outside of my district," Braley wrote. "I'll pledge to them, just like the people of Eastern Iowa that I will listen, work hard, and get things done for Iowa's middle class."

Whether he will have any Democratic challengers for a primary remains to be seen. Also unknown: which Republican will step forward to oppose him.