Joe Kennedy kept his head down for his first couple terms in Congress. Then Trump became president

Representative Joseph P. Kennedy’s emergence among Democrats was evident when he gave their response to 2018 State of the Union.Matthew J. Lee/Globe staff/Globe Staff

In a head-to-head comparison of legislative accomplishments, there’s little doubt Representative Joseph P. Kennedy III has a shorter list than the Democrat he may challenge next year — Senator Edward J. Markey, who, after all, has been in Congress longer than Kennedy has been alive.

But supporters say Kennedy’s nearly seven years in the House demonstrate the 38-year-old’s ability to capture and shape public imagination. It’s a record that is harder to quantify than mere bills introduced and passed, they argue, but is nonetheless crucial to the Democratic Party as it seeks to return to power in the Senate and regain the White House.

Described by colleagues as humble despite his pedigree, the Newton Democrat kept his head down during his first two terms, eager to build credibility through a handful of signature policy issues, allies say. Immigration, transgender rights, health care, gun violence, and economic justice have been key areas for Kennedy, whose district runs south from affluent Brookline to the struggling industrial city of Fall River.

But after President Trump took office, Kennedy started to raise his profile by speaking out against the controversial policies of the administration and House Republicans, who were still in power.

A minute-long, middle-of-the night House committee speech he gave in 2017 criticizing GOP efforts to repeal Barack Obama’s health care overhaul as “an act of malice,” was viewed close to 10 million times within days. Another clip of him pressing GOP lawyers over cuts the Republican health care bill would make to mental health care coverage — an issue he has focused on from the start of his House tenure — drew 4.9 million views.

This star power and oratorical skills on brand with the family legacy landed the red-headed grandson of Robert F. Kennedy the Democratic response to the 2018 State of the Union. It’s a coveted but high-stakes speaking slot for aspiring members in the party out of power, and Kennedy received mostly good reviews for his dispatch from a technical high school in Fall River.

Last fall, shortly after the 2018 midterm elections brought Democrats control of the House, Kennedy delivered a well-received speech calling on Democrats to adopt what he called “moral capitalism” to counter the narrative offered by Trump and conservatives more broadly. The vision he offered was of a capitalism that would be judged, he said, “not just by how much it produces, but how widely it shares; how good it does for how many; and how well it takes care of all of us.”

The speech amounted to an effort to guide his party toward a vision for how to tackle one of the most salient issues facing the country: the growing divide between the very rich and everyone else.

The Democratic Party is in a moment of generational change, in search of the next crop of leaders, and “Joe Kennedy needs to be one of those leaders,” said one national Democratic lawmaker. “The Senate gives him the best chance to do that.”

Kennedy skeptics, including some who like him just fine, argue his legislative record is thin, especially compared to Markey’s and particularly on the urgent issue of climate change. They say they see no compelling argument for throwing out Markey, no matter Kennedy’s ambitions or the cachet of his name.

Caroline Bays, a liberal activist from Watertown, called Kennedy “an inexperienced congressman who hasn’t particularly distinguished himself” and focused on Markey’s leadership on climate change in her weekly e-mail newsletter, which goes to about 400 fellow activists.

“This is such an important time in our history that we shouldn’t be primarying the leading Senate voice on such an important issue,” she said in an interview with the Globe, noting that her message prompted a lot of positive responses.

Some in the party’s left wing also perceive Kennedy as too moderate. They chafed over his delay in embracing Medicare-for-All. Kennedy signed on to the House bill this year after he said its authors addressed his concerns, including that earlier versions would hurt reproductive rights and force regional hospitals to close.

His long opposition to marijuana decriminalization efforts also riled some on the left. Kennedy announced a change of heart last fall, just as the first recreational pot shops opened in Massachusetts.

Supporters say Kennedy’s work on transgender rights typifies his approach to elected office, the way he uses his profile to raise up the marginalized. Gay and trans rights advocates say he goes beyond signing onto legislation to elevating the everyday experiences and struggles of trans people to the mainstream.

Kennedy was active on the issue as early as his first year in office, as transgender advocates started pushing for a state law to bar discrimination against them in such public places as restaurants, bars, and athletic facilities.

He submitted written testimony supporting expanded transgender protections to the Massachusetts Legislature in 2013. That year, his college roommate at Stanford, Jason Collins, cited Kennedy’s participation in a 2012 Gay Pride parade as inspiring his decision to come out as the country’s first openly gay professional basketball player.

Mimi Lemay, a Melrose mom whose 5-year-old son had recently transitioned, remembered tears in Kennedy’s eyes as she described her family’s experience at a roundtable for the bill.

“Afterwards he came up to us and assured us he was going to do everything in his power to make sure that our son felt safe and that he was sorry that we even had to fight for this,” Lemay recalled.

In Kennedy, she and the rest of the trans community found a “genuine champion,” she said, which surprised her given his privileged background.

Among the moves Kennedy made on behalf of the Massachusetts bill: In 2016, he very publicly asked to have his name removed as a co-host for a gala hosted by the National Gay & Lesbian Chamber of Commerce when he learned the group planned to honor GOP Governor Charlie Baker with an award. Kennedy’s reason: Baker’s “refusal” to support the transgender bill. (Kennedy returned to the co-host list after the group disinvited Baker.)

“I believe that that was the tipping point” for the legislation, said Lemay, which the Legislature subsequently passed and Baker signed. “I‘m sure it was risky. I’m sure he ruffled many feathers doing so. But he stood up for us.”

In the wake of Trump’s attempts to ban transgender people from the military, Kennedy invited a transgender Army staff sergeant, Patricia King, to be his guest to the 2018 State of the Union. Before that, Kennedy had helped King secure approval for her gender reassignment surgery when she ran into bureaucratic resistance.

Kennedy, who declined to be interviewed for this story, has notched some legislative victories. He was the lead sponsor of the high-profile resolution denouncing the Trump administration’s ban on transgender men and women serving in the military, which passed the House earlier this year with the support of every Democrat and a handful of Republicans.

Republicans controlled the House for most of his time there, and his record includes several bipartisan measures that became law. In his first term, he teamed up with a Republican colleague to spur domestic manufacturing, leading to the Massachusetts Institute of Technology landing a new manufacturing institute focused on textiles.

Other wins include bills that passed the House to expand education and job training for low-income students and legislation championed by his colleague in the Senate, Elizabeth Warren, that allows hearing aids to be sold over the counter.

Representative Sean Patrick Maloney, a New York Democrat elected the same year as Kennedy and one of his closest allies in the House, said Kennedy both throws himself into the policy weeds and also understands the politics of getting things done.

“Not that many members of Congress think with both sides of their brain,” he said.

“Joe has an enormous contribution to make, and I want to see him given that opportunity in whatever way makes the most sense for him, his family, and the people he represents,” Maloney said. “He is someone who really can make things better.”