Washington (CNN) - Rep. Brad Ellsworth of Indiana will announce Friday that he's decided to make a bid for the seat now held by retiring Sen. Evan Bayh, a Democratic party source tells CNN.
Bayh delivered a major blow Monday to the Democratic Party, when he announced that he would not run for a third term this November.
Ellsworth, first elected in 2006, represents Indiana's eighth congressional district, which is located in the southwest part of the state. The former county sheriff won 61 percent of the vote in his first election, and grabbed 65 percent in his 2008 re-election. Ellsworth, 51, is telegenic and has a moderate voting record that will help him in a swing state like Indiana.
Ellsworth's announcement that he will run for Bayh's seat appears to be major coup for the Democratic Senatorial Campaign Committee, which was hunting for a strong candidate to defend the seat. The move could also put the Democratic Congressional Campaign Committee in a bind, as they will most likely now have to defend an another open seat in the House of Representatives. Ellsworth's district went for John McCain by 4 points in the 2008 presidential election and President Bush won the district by 24 points in 2004.
The Indiana Democratic Party's Central Committee will select the party's senate candidate, since no candidate filed the needed signatures to qualify for the primary ballot. The committee must wait until after the May 4 primary to select their candidate. Other state Democrats may be considering a run for Bayh's seat, although Ellsworth is the first to announce.
Bayh's unexpected announcement gives national Republicans one of their best opportunities to takeover a Democratic seat, according to independent analyses from two leading non-partisan political handicappers. The Cook Political Report revised its rating for the Indiana contest to "Leans Republican" shortly after news of Bayh's decision broke. The race had previously been rated "Leans Democratic." The Rothenberg Political Report modified its rating from a "narrow advantage" for Democrats to "toss-up," meaning the race could go either way.
Both Cook and Rothenberg had Bayh as a lock for re-election until the announcement earlier this month that former Republican Sen. Dan Coats, who once held Bayh's seat, was mulling a challenge. According to Cook and Rothenberg, a Bayh-Coats match-up would have been competitive, with a slight advantage for Bayh as the incumbent.
The story was first reported nationally by the Washington Post.
CNN's Robert Yoon contributed to this report