Story highlights Former Sen. Evan Bayh will seek his seat again, a source told CNN on Monday

His move makes competitive another seat Democrats hope to win in order to gain a majority in the Senate

(CNN) Evan Bayh is mounting a return bid to the U.S. Senate, giving national Democrats a boost as they aim to retake the chamber in November.

An announcement about Bayh's candidacy for the Indiana Senate seat is expected soon, a source familiar with the plans said on condition of anonymity. Initially expected Monday, the formal announcement has been delayed because of logistics.

National Democratic leaders have encouraged Bayh to run for more than a year, ever since incumbent GOP Sen. Dan Coats announced he would not run again.

Sen. Chuck Schumer, who is in line to be the Senate Democratic Leader after Sen. Harry Reid retires, heavily lobbied Bayh to get in the race, said a senior Democratic leadership aide. Bayh was dismissive at first, insistent he was done with public life, but Monday's announcement will mark a significant victory for Senate Democratic recruiters.

Rep. Todd Young won the hotly contested Indiana Republican primary, beating out Rep. Marlin Stutzman for the nomination. Young has been heavily favored to beat Baron Hill in November, but Bayh's entry into the race easily changes that dynamic.

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