Mayor Martin Walsh has endorsed US Rep. Michael Capuano in the Democratic primary for the Massachusetts Seventh Congressional District where the ten-term incumbent is facing a challenge from Boston City Councillor At-Large Ayanna Pressley.

Standing outside the Boston Pizza & Grill, next to the Strand Theatre, the backdrop to many a Walsh campaign event, the mayor told a crowd of supporters that Capuano is “fighting for the rights of people across the country but the people of this district first and foremost.”

Walsh said Capuano could lead key committees should the Democrats take the House back from the Republicans in the midterm elections, putting Massachusetts and Boston in a strong position to advocate locally on the federal level.

In the early Obama years, Walsh said, Congress cared about healthcare, environmental justice, housing, transportation, and the working class. “We’ve lost that Congress,” he said, “and for the last eight years the Congress that’s been in place down in Washington is trying to take away all those rights of all the American people across the country.”

After thanking the mayor for his support, the 66-year-old Capuano said the incrementalism that marks much of local politics is not the case in Congress, where battles rage over Supreme Court seats, healthcare, taxes, Social Security, subsidized housing, and unions.

“My whole life, like Marty’s whole life, has been dedicated to leveling the playing field as much as we can, “ he said, “Letting everybody be judged on their own.”

Although there is scant daylight between the two candidates’ policy positions, the 44-year-old Pressley says she will bring a new lens to Congress. The Ashmont resident has been forceful in pushing for more compassion and more resources for vulnerable and historically underserved populations.

The district includes most of Boston, parts of Cambridge and Milton, and all of Chelsea, Everett, Randolph, and Somerville. It is the state’s only majority-minority congressional district – a notable feature with the Democratic primary shaping up as a race between a black woman and an Irish-Italian man.

Throughout the summer, Capuano said, he will be out on the doors and on the streets. “This is gonna be a tough fight, I know that,” he said. “I'm not taking anything lightly… there’s never been a moment of my life when I didn’t leave everything on the field.”

Wilnelia Rivera, senior advisor to the Pressley campaign, said in a statement that the campaign is focusing on engaging with voters. "Over the past few weeks, we have heard the encouraging voices of support from people in this district who see themselves in this campaign," she said, "from union hotel workers and electricians in the City of Boston to grassroots community leaders in Chelsea and Cambridge and countless others, including many who have chosen this moment to be involved in politics for the first time. Their stories, and the urgency of their challenges that too often go unheard, is what continues to propel this campaign forward."