If the campaign season from Labor Day to Election Day is a 400-meter sprint, the race from Labor Day to Delaware’s open congressional primary on Sept. 13 is a 50-meter dash. 

The three major Democrats vying for Delaware’s at-large seat have less than a week to make their case to voters who are just tuning in. 

This seat wasn’t even supposed to be open. Current Democratic Rep. John Carney is running for governor in the First State, but he wouldn’t have sought the job had former Attorney General Beau Biden not died last year.

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The six-way Democratic primary has been a sleepy contest, with just one public poll conducted in July that showed 53 percent of voters undecided. 

But whoever wins will almost certainly become the third member of the state’s congressional delegation, and could potentially diversify the racial and experiential ranks of Congress.

Delaware is one of just three states that has never sent a woman to Congress. In Lisa Blunt Rochester, the state’s former Labor secretary, voters have the chance to change that — and to elect the state’s first African-American at the federal level.

“Some things are obvious,” Rochester said Tuesday about what separates her from her opponents. “I’m African-American, and I’m a woman. I think that does add a level of richness and experience to the position.”

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EMILY’s List helped get Rochester’s campaign off the ground. She’s received either financial assistance or mentoring from several House Democratic women involved in female recruitment for the party, like Florida Rep. Lois Frankel, New York Rep. Grace Meng and Illinois Rep. Cheri Bustos.

California Rep. Karen Bass and New York Rep. Yvette D. Clarke have been particularly helpful mentors, Rochester said. The Congressional Black Caucus PAC, as well as many individual members of the caucus, have donated to her campaign. 

VoteVets Action Fund, a progressive group that seeks to elect veterans to Congress, has so far put $200,000 behind 2014 Democratic state Treasurer candidate Sean Barney.

Barney, a Marine veteran who’s been open about his experience with post-traumatic stress disorder, received the Purple Heart for his service in Iraq.

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Veterans like Arizona Rep. Ruben Gallego, Massachusetts Rep. Seth Moulton, California Rep. Ted Lieu and Minnesota Rep. Tim Walz have all contributed to Barney’s campaign. Only about 20 percent of members of Congress have served in the military, down from more than 70 percent in the 1970s. 

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State Sen. Bryan Townsend is the only legislator in the mix. He was tied with Rochester at 11 percent for the lead in the July Fairleigh Dickinson/News Journal poll of registered voters. Barney came in fifth at 4 percent.

It’s still a wide-open race that will likely come down to name recognition and turnout.

“Late TV is the key here,” VoteVets Chairman Jon Solz said. VoteVets and Barney’s own campaign each have their own ad that touts the candidate’s military and government service.  

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Rochester has launched three ads, mostly focusing on her commitment to equal pay and health care for women and job creation. She loaned her campaign an additional $225,000 in the final two weeks of the campaign — on top of the $179,000 she had already poured into her race — to keep pushing out her message.

But Townsend disagrees that TV is the proper strategy and insists that it’s a two-person race between him and Rochester. He’s chosen to spend his money on targeted mail, arguing that expensive Philadelphia TV buys are inefficient, especially in a state known for retail politics. 

All three candidates boast strong First State political connections. Townsend has a small base from his service in the legislature, but he’s picked up backing from many of the largest state and local labor groups.

Besides serving in two gubernatorial administrations, Rochester headed the Wilmington Urban League. Her father was president of the Wilmington City Council and her sister served as state director for the Obama-Biden campaign. Hunter Biden, the second son of Vice President Joseph R. Biden Jr., has donated to Rochester’s campaign.

After working as a legislative assistant for Democratic Sen. Thomas R. Carper, Barney was campaign manager and policy director for Gov. Jack Markell, also a Democrat. 

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In such a small state, it’s not surprising that the delegation is remaining neutral. Carper’s leadership PAC donated $1,000 to both Rochester and Barney in late August. The state Democratic party, which usually endorses, decided not to this year. 

Barney raised the most money during the second quarter and the pre-primary reporting period, but he’s been attacked for a high percentage of out-of-state donations. The founder and CEO of Starbucks, the president of the New York Knicks, former Massachusetts Gov. Deval Patrick, and a host of academics have all chipped in. 

Barney maintains that his campaign has a strong grass-roots fundraising operation, and that his out-of-state donations come from people who want to see another veteran in the House.