Updated at 5:30 to include video of Lone Star Politics debate.

The Democratic race for the 32nd Congressional District — a referendum on who is best suited to beat incumbent Republican Pete Sessions — has come down to a voter turnout fight between two candidates who agree on most issues.

Colin Allred and Lillian Salerno have intensified their grass-roots efforts in hopes of getting fatigued voters back to the polls. That's not easy, considering there have already been three elections this year, including two in May.

Allred beat Salerno in the March 6 primary, gaining 38 percent of the vote to her 18 percent in a seven-person race.

Tuesday's showdown has become sharper in tone, as Allred tries to hold his lead and Salerno attempts to change minds.

While they agree on issues related to health care, immigration and gun control, they clash on the question facing most undecided voters: Which candidate can beat Sessions?

"I'm thankful and honored that the people in this district have gotten me this far," Allred said. "We are not taking anything for granted. We are really working hard."

Salerno said she has momentum and has knocked on 59,000 doors.

Voter Joe Pacetti meets with Lillian Salerno, Democratic candidate for the 32nd Congressional District, as she greeted voters outside Our Redeemer Lutheran Church in Dallas on Sunday. (Ben Torres / Special Contributor)

"We think we have an amazing ground game," she said. "When we go to the doors and people hear our story on how we're going to beat Pete Sessions, if they are undecided, they come over to our side."

Most of the themes from the first round remain the same. Allred is casting himself as a homegrown talent who wants to give back to the district that paved the way for his success.

Salerno, who was the only woman in the Democratic field, say that she's uniquely suited to beat Sessions and that her life experience as a mother, businesswoman and public servant is needed in Washington.

"In a runoff, you have got to identify your supporters and get them back out to the polls," said Matt Angle, a Democratic strategist and director of the Lone Star Project. "Peer-to-peer contact is the best way. You need neighbors talking to neighbors."

Days before the runoff, Allred and Salerno exchanged salvos during Friday's recording of Lone Star Politics, the political show produced by KXAS (NBC5) and The Dallas Morning News.

Salerno said she has been "tested, vetted and has more experience."

"My opponent, Allred, hasn't had the kind of experience that I have had," she said. "I know what it take to get stuff done. ... In ordinary times, Colin would make a good congressman. These are not them."

Allred said Salerno's campaign is desperate.

"I think it's kind of ridiculous," Allred said. "Sometimes campaigns get desperate. They start swinging for things and looking for avenues to draw some distinctions that are not there."

Lone Star Politics airs 8:30 a.m. Sunday on NBC5.

Looking for women's votes

Female voters could be critical in the contest. For the first round, Salerno aimed her campaign almost exclusively at women. She plastered the district with several campaign mailers that nodded to the movement against sexual harassment and assault and the need to have more women leaders in Congress.

As she greeted voters at the polls, Salerno said women are critical to her success, but added that her campaign is aimed at all voters.

"They got me here," she said. "What they're seeing now, as well as men, is that we've got to have that seat."

One of her supporters, retired Dallas paralegal Audrey Monlezun, said Salerno has far more experience in government, business and fighting for equality than Allred.

"I believe that Lillian Salerno is definitely the most experienced and qualified woman running for Congress in the state of Texas and a proven fighter for those who need support and protection," she said. "We haven't elected a woman to Congress in 22 years."

Colin Allred, Democratic candidate for Congress, spoke recently at Lovers Lane United Methodist Church during a small group discussion on gun violence. Justin Irwin, a student at Marjory Stoneman Douglas High School in Parkland, Fla., spoke to church members about the day of the school shooting and his friend Nicholas Dworet, who was killed. (Rose Baca / Staff Photographer)

But Allred, as his numbers suggest, has also done well with women.

"What women voters are looking for is someone who speaks to their aspirations and the issues that are important to them," Allred said.

Dallas education advocate Mita Havlick, who supports Allred, said he has the coalition needed to beat Sessions.

"Colin's message is much more inclusive. It wasn't targeted at a specific group," she said. "He's included all the demographics in his campaign and I've always felt included, as a woman.

"For us, the biggest thing is to beat Pete Sessions in the fall and Colin can do that."

Experience a focus

In her effort to close the gap with Allred, Salerno is trying to convince voters that her experience makes her the better candidate.

She developed a small business that manufactured retractable needles. She's a lawyer and has been a part of several high-profile campaigns, including former Houston Mayor Bill White's campaign for governor. Salerno served as deputy undersecretary for rural development at the Department of Agriculture in Barack Obama's administration.

"The district needs somebody who is vetted and tested," Salerno said. "They don't feel that way about Colin Allred."

Salerno said Sessions is putting together background on both candidates.

"I'm an open book," she said. "My opponent Allred is not an open book, and that's problematic."

Allred, a former NFL linebacker, became a civil rights lawyer when his career ended. He worked on former Texas Sen. Wendy Davis' 2014 campaign for governor. He spent five months in the Department of Housing and Urban Development under former Secretary Julian Castro.

"Good ideas and vision just don't come from being in Washington," Allred said. "I know what our people are facing. ... I have a story to tell about what happens, what people can do when you give them a chance."

Allred has rallies and canvassing efforts planned this weekend featuring some of his key supporters, including Davis.

Salerno has rallies planned in Garland and Lakewood.