Democratic officials say former Democratic Sen. Evan Bayh is expected to make another run for Senate in Indiana.

The surprise development could dramatically improve Democratic chances to win the vacant seat and possibly take back control of the Senate.

Republican Sen. Dan Coats is retiring from the seat. The primary already happened and former Democratic Rep. Baron Hill won the nomination, but he filed papers Monday to withdraw.

Bayh retired from the Senate in 2010 following two terms. He has been sitting on about $10 million in campaign funds.

The Democrats spoke on condition of anonymity ahead of a public announcement.

The development was first reported by CNN.