"I believe we need to fight for more educational opportunity, better jobs and to get guns out of the hands of criminals and gangs that are preying on our neighborhoods. I believe Robin Kelly is the right candidate to pick up that cause to fight for the people of Chicago and the Southland," he said in a statement issued by Kelly's campaign.

Top contenders in the race include Democrats Kelly, former Rep. Debbie Halvorson, state Sen. Toi Hutchison and Alderman Anthony Beale. The seat, vacated by Rep. Jesse Jackson Jr. (D-Ill.), is heavily Democratic, and whoever makes it through the Feb. 26 Democratic primary is expected to easily win the general election.

Halvorson has clung to a tenuous lead in the Democratic primary so far because of her high name identification in the fractured field.

But she was recently attacked by pro-gun-control super-PAC, Independence USA, which is bankrolled by New York City Mayor Michael Bloomberg (I), for her support of gun rights, a move that could badly damage her chances at returning to Congress.

Kelly, in fact, noted her own "F" rating from the National Rifle Association in the release announcing Harris' endorsement.

"The voters of the second district deserve someone in Congress who they can trust to stand with President Obama to take on the NRA," she said.

"While some of my opponents have A ratings with the NRA, I couldn’t be more proud of my F rating and it’s that record that I will take to Congress to fight for the families across Chicago and the Southland,” Kelly added.

--This post was updated at 5:11 p.m.