Democrats are driving toward a primary collision course in Illinois, where the party could endure a multimillion-dollar slugfest in a race essential to capturing Senate control in 2016.  

A fourth House Democrat, Rep. Robin Kelly, told CQ Roll Call she is weighing a bid against GOP Sen. Mark S. Kirk. She joins the growing list of members considering bids, including Democratic Reps. Cheri Bustos, Tammy Duckworth and Bill Foster.  

“I’m just doing my due diligence to look at if there is a pathway in the Senate race,” Kelly said in a phone interview after votes on Wednesday afternoon. “If I feel like I find a pathway for me then I will do it, irregardless” of who else runs.  

Democrats do not expect all four House Democrats to enter the race. But even if just two House members run for Senate, Democrats could endure the most contentious primary for a competitive Senate seat in six years. Kirk, who faces re-election in a state President Barack Obama carried by 17 points in 2012, nears the top of the Democratic target list  as the party aims to pick up the five seats necessary to ensure Senate control.  

Senate Minority Whip Richard J. Durbin, who has personal and political ties to a number of Democrats mulling bids, said he does not fear a bloody primary.  

“I think there’s going to be a process and a hierarchy of decisions. We’re going through that right now,” Durbin told CQ Roll Call. “I think at the end of the day it’s likely the potential field will diminish, down to one or two very serious candidates.”  

But a spokesman for the Democratic Senatorial Campaign Committee declined to comment on whether it would intervene in the primary. And operatives in the Land of Lincoln said convincing Democrats to sit the race out could be tough.  

“We kind of just duke it out in our federal primaries,” said Tom Bowen, a former political director for Chicago Mayor Rahm Emanuel.  

Multiple Democrats said Duckworth, a veteran who represents the Chicago suburbs, would be the favorite in a primary. Democrats describe her triumphant personal story — she lost both her legs and sustained damage to her arm when a helicopter she co-piloted in Iraq was shot down in 2004 — as a positive in a statewide race.  

They believe her profile also makes for a strong match against Kirk. He is a veteran who faces mobility challenges after suffering a stroke in January 2012.  

But Democratic operatives say all four House Democrats have a path to a primary victory.  

Bustos has proved to be a successful campaigner, raising millions to win two races in a tough district in the northwest corner of the state. She confirmed she’s looking at the race in an interview with CQ Roll Call earlier this week.  

Foster, first elected to Congress via a special election in 2008, has been on television in the Chicago suburbs for four cycles. He represents a key geographic region for success in a general election. He has also extensive personal resources to fund a campaign, ranking as the 51st wealthiest member  of Congress.  

And Kelly, who is black and represents a majority-minority district, would have an advantage with the roughly 30 percent of black primary voters in the state. Kelly also came to Congress via a special election in 2013.  

Durbin will be an influential player in navigating the primary. Yet Democrats say ambitious Illinois members could choose to enter the race without his blessing. Duckworth knows that scenario well.  

In 2006, she ran for retiring GOP Rep. Henry Hyde’s seat in the Chicago suburbs. National Democrats, including Durbin and Emanuel, lined up to support Duckworth, who faced a bruising primary against former nominee and technology consultant Christine Cegelis. Duckworth won the primary but ultimately lost the general election to Rep. Peter Roskam by 3 points.  

Local Democrats expect candidates to start announcing in late February or early March, following the mayoral elections. That would give the Senate candidates a year to raise the millions necessary for the March 15, 2016, primary.  

“Primary candidates are pretty smart,” one national Democratic operative said. “You think to yourself, ‘Jesus, are we creating a situation where we’re shooting ourself in the foot?'”  

The Illinois Senate race is rated a Tossup  by the Rothenberg & Gonzales Political Report/Roll Call.  

Kyle Trygstad contributed to this report.
Related:

Tammy Duckworth: I’m ‘Taking a Real Serious Look’ at Senate Run


Cheri Bustos Keeps Door Open to Senate Run


Senate Race Ratings from the Rothenberg & Gonzales Political Report/Roll Call


10 Races to Watch in 2016: Illinois Senate


Congressman Mum on Illinois Senate Race


The 114th: CQ Roll Call’s Guide to the New Congress


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