On Sunday morning, a day after Rep. Joe Kennedy III officially announced that he’s running for the Senate seat currently held by fellow Democrat Ed Markey, Myrna Cohen stood in front of an American Legion post in Newton and waved an “Ed MARKEY for US Senate” sign at passing traffic, awaiting Markey’s arrival at a gathering of the Newton Democrats.

Cohen’s motives were twofold. As you’d expect, she’s a Markey superfan.

“Ed Markey represents not only knowledge and experience, but decency,” Cohen said. “And decency is what this country needs to have now.”

Cohen, 83, also said she's deeply unimpressed with Kennedy’s decision to run.

“I think Joe Kennedy should mind his manners,” Cohen said. “I have a lot of problems with the way Joe Kennedy has done this.”

The Markey supporters who held signs next to Cohen were, for the most part, cut from a similar cloth. They were on the older side, passionately supportive of Markey, and dismayed by what they believe Kennedy’s primary challenge says about the congressman's character — a point they conveyed in that distinctive tone older people use when speaking about younger people who’ve let them down.

“Ed has really been in the forefront of everything I ever cared for,” said Martina Jackson, 78. “Health care. Women’s right to choose. He’s been a great spokesman for immigration. He’s been terrific on climate change long before, I think, it was on anyone else’s radar screen.”

And Kennedy?

“I am really disappointed,” Jackson said. “I feel that he’s betraying us as Democrats. He’s betraying himself.

“In the last election cycle, Joe was helping Democrats to become members of Congress,” she added. “And now, when we need [to flip the Senate], for Joe to do this … it’s insulting, and it’s demeaning, and it doesn’t make his case.”

Robert Cohen, Myrna Cohen's husband, was terser.

“We’re going to lose 20 years of experience and knowledge if we lose Ed,” said Robert Cohen, 85.

Kennedy “is a nice guy,” Robert Cohen added. “My grandson interned for him. ... But this is not the time for him to run.”

There is, to be sure, reason to take these objections with grain of salt. Recent polling suggests that Kennedy enters the race as the frontrunner, an enviable position for any politician challenging an entrenched incumbent. If the prospect of a younger man trying to take an older man’s job gives some voters pause, it seems to be a manageable problem.

That said, it’s worth remembering the backlash that Kennedy’s colleague Rep. Seth Moulton experienced earlier this year, when he argued that Nancy Pelosi should be replaced as House Speaker. While some saw sexism in Moulton’s push for new leadership, others saw ageism, or some combination of the two. The backlash was fierce, and now, after a short-lived presidential bid, Moulton faces two primary challengers of his own heading into 2020.

Still, if some Massachusetts voters see Kennedy as a young man in a hurry, others may decide that his relative youth — he’s 38, while Markey is 73 — is appealing. Adding to the potential upside: To state the obvious, he’s not just any young politician, but a young Kennedy, which is a political brand in and of itself.

After a Kennedy campaign event Sunday afternoon in New Bedford, at which he talked up the city’s burgeoning offshore wind industry, Diane Hunt of Fairhaven made it clear that for her, the age factor works in Kennedy’s favor, not Markey’s.

“I’m not anti-Markey, but I just think we need youth,” Hunt said.

“Here’s a progressive and intelligent, youngish man — much younger than me, but that’s what we need,” said Hunt, 58. “We need to get away from the past and think toward the future.”

Echoing that argument was Derrick Dupras of Laborers’ Local 385, one of several union members who showed up to support Kennedy’s campaign.

“Joe’s young, he’s full of energy, he’s got great ideas, and he’s very smart,” Dupras said. “I see that as the future.”

When Kennedy was asked what he’d say to older voters who sense ageism in his Senate bid, he responded, essentially: Give me time to make my case.

“I appreciate that concern,” Kennedy said. “I obviously disagree with it. I’ve got the course of a campaign to prove it.

“I believe that on critical issues facing our country, that there are real differences,” Kennedy added, citing his desire to eliminate the electoral college and Senate filibuster. “I’m confident of that. I look forward to making that case to voters across the commonwealth. And we’ll see what happens.”

For Markey, meanwhile, a question looms: How best to handle the difference between Kennedy’s age and his own? Turn it into a laugh line, a la Ronald Reagan in 1984? Or assert, earnestly, that anyone who thinks Kennedy has more energy than him is mistaken?

While the race is just getting started, on Sunday, Markey made a comment that suggests he favors the second option.

“I wake up every morning,” Markey said, “energized to fight Donald Trump.”