Congressman Mike Capuano and his challenger for the 7th Congressional District seat in next month's primary. Boston City Councilor Ayanna Pressley are set to debate this evening on television on WGBH 2 starting at 7 o'clock and we’ll be carrying it here on the radio 89 7 WGBH as well. WGBH Radio's Adam Riley has been following the campaign and spoke with WGBH All Things Considered host Barbara Howard. This transcript has been edited for clarity.

Barbara Howard: So Capuano, he's held that seat in Congress since 1999. Pressley has sat in the Boston City Council since 2010 and she's posing the biggest threat to Capuano in a long time, maybe even ever. What's she been running on?

Adam Reilly: Her big claim, as I read it, is that Capuano’s approach to being a Congressman is antiquated. She accuses him essentially of sitting in Washington, voting the right way when he has a chance to, and hoping that the Democrats retake the House so he gets to do a little more. She says that in the Trump era that is simply inadequate, that it's not enough to vote the right way when you have a chance, but you need to push back aggressively and creatively. She says if she is elected, she would take more of an activist approach. She's also talked about what she calls pervasive inequality in the 7th District. Her strong implication is that Capuano has not paid enough attention to addressing that inequality. She says she would if she's elected and that she would bring a different perspective as an African-American woman.

Howard: And what has Capuano had to say about why he should keep his seat in Congress?

Reilly: I will paraphrase again. I think his contention, although he doesn't use the word, is that Pressley is being a little bit naive. He has said explicitly that it takes a long time to learn how to work effectively inside of Congress and that in his nearly two decades in Washington, he has done so.

He's talked at great length about his abilities to secure federal money for the district for things like community health centers and affordable housing and transit infrastructure. The implication there, of course ,is that if Pressley wins, she might not be able to deliver the same way he says he has. And he's talked up the endorsements he's received, in particular, former Governor Deval Patrick and Congressman John Lewis, the civil rights icon.

Howard: How competitive is the race looking?

Reilly: It is close enough to be interesting. The polling that's been done on the race has shown Capuano with a low double digit lead, so comfortable maybe not insurmountable. It's also shown Pressley doing better than Capuano among young voters and voters of color so it's not a blowout. It is still competitive.

Howard: Is Pressley’s challenge to Capuano emblematic of a bigger trend playing out in Democratic politics so far this year?

Reilly: I think it is and it isn't. We have seen again and again seemingly entrenched incumbents getting challenges from people who aren't taken seriously as challengers and then end up winning. Exhibit A of course is Alexandra Ocasio-Cortez who beat a 10-term incumbent Joe Crowley in New York. There are some parallels between that race and this one in particular when it comes to demographics.

You have a younger woman of color taking on a longtime incumbent who is a white man. But there are also some big differences that are worth highlighting. Ocasio-Cortez is a democratic socialist. She's a Bernie Sanders Democrat. Ayanna Pressley was a Hillary Clinton supporter. She's also very much a liberal establishment Massachusetts Democrat. She used to work for John Kerry and Joe Kennedy II. So on issues, she and Capuano are actually pretty similar, but when it comes to methods and when it comes to identity, there are starker differences.

Howard: And anything we should be watching for or listening for on the radio, in tonight’s debate?

Reilly: I'll tell you what I am going to be most interested to watch and listen for. In their previous debate at UMass Boston, Capuano sort of lost his cool at one point where he felt like he wasn't being given enough of a chance to rebut Pressley's criticisms. He lost his cool in a way which I would argue if you're an undecided voter was not beneficial to him. There was also a moment where Pressley, I thought, sort of bristled a little bit when she was asked about the role of race and ethnicity saying that well it was important that she's an African-American woman she didn't want to be reduced to that or have her candidacy reduced to that. So I'll be watching to see which of these candidates, if either one, does lose their cool and maybe gives their opponent a boost.

Howard: OK. Thanks Adam.

Reilly: Thanks Barbara.

Howard: That's WGBH Radio's Adam Reilly. He's been following the race between Congressman Mike Capuano and his challenger Boston City Councilor Ayanna Pressley.