(CNN) - Gun control is front and center in the first congressional special election of 2013, a Chicago contest that's also feeling the heavy involvement of New York City's mayor, who's spent more than $2 million on the race.
Tuesday's primary election is the first step in filling the vacant seat in Illinois' second congressional district, which until recently was held by Democrat Jesse Jackson, Jr., who pleaded guilty in federal court last week to using campaign funds for personal use.
The election is the first congressional contest since December's mass shooting at Sandy Hook Elementary School in Newtown, Connecticut, which put gun control back into the national political spotlight. And the district includes some areas hit hard by the increased gun violence in Chicago. Some 535 people were murdered in the city last year, according to local crime statistics, up from 433 in 2011. January already set a bloody record, with some 43 people killed.
There are more than a dozen candidates vying for the Democratic nomination, where the winner needs a simple plurality. And in the district, which includes parts of Chicago's South Side and has long been dominated by Democrats, the winner of the party's primary will be considered the frontrunner in the April 9 general election.
Jackson, who held the seat for 17 years, was a reliable vote in favor of gun control. Some polls last month suggested former Rep. Debbie Halvorson, who had an "A" rating from the National Rifle Association, and who opposes an assault weapons ban, was a leading contender in the Democratic primary.
Enter New York City Mayor Michael Bloomberg, a leading advocate for gun control. His Independence USA political action committee has spent more than $2 million to run spots on Chicago television attacking Halvorson's position on gun control. Bloomberg's campaign also spotlights state Sen. Toi Hutchinson, who also had an "A" rating from the NRA.
Bloomberg's PAC is backing former state Rep. Robin Kelly, a strong supporter of gun control efforts.
"There is no question the New York City mayor's multi-million dollar investment has had an outsized impact in the race," says Jessica Taylor, senior analyst and reporter for the non-partisan Rothenberg Political Report. "The Independence PAC has been carpet bombing the district with expensive broadcast TV ads boosting Kelly, and Kelly is the only candidate with enough money to go up on cable, also with an ad touting her record on gun control."
Halvorson is white, while Kelly and Hutchinson are black. Hutchinson dropped out of the race two weeks before primary day, as she came under attack by the commercials from Bloomberg's PAC, but also amid concerns that she and Kelly would split the African American vote.
Gun control has long mattered in Chicago elections and the Sandy Hook shootings have put the issue back in the spotlight nationally. The big question is whether the controversial issue will continue to dominate as next year's midterm elections draw closer.
"While it's very easy for a special election to become an incubator for the national issue of the day, it is less clear the issue will resonate on a national scale in 2014," adds Taylor.