Senate Democrats' top campaign spending group is wading into Mississippi's U.S. Senate race for the first time this year, an aggressive move in a deep-red state that signals a party on the offensive as Republicans look to protect a slim majority.

The Senate Majority PAC will spend $1. 2 million on a new television advertisement to boost Scott Colom, a district attorney, in his campaign against Republican Sen. Cindy Hyde-Smith.

The ad, first disclosed to The Associated Press, is set to start Wednesday and run through Election Day.