Jon Keller is the political analyst for WBZ-TV News. His "Keller @ Large" reports on a wide range of topics are regularly featured during WBZ News at 5 and 6 p.m.

The opinions expressed below are Jon Keller's, not those of WBZ-TV, CBS News or Paramount, a Skydance Corporation.

Massachusetts Congressman Seth Moulton officially announced Wednesday he's running against 79-year-old Sen. Ed Markey in the 2026 U.S. Senate race.

"I just don't think we can wait six years for new leadership in our party," Moulton, 46, a Democrat who represents the Sixth District, north of Boston told WBZ-TV. "The status quo is not working, and our party leaders are clinging to that old playbook that's gotten us two terms of Donald Trump."

It's an argument former Congressman Joe Kennedy made - and emphatically failed to capitalize on - when he challenged Markey back in 2020. Markey has been in public office for 52 years, 49 of them in Congress.

But times have changed. The second Trump term has terrified Democrats and others from the center leftward; the generic polling on which party's candidate voters prefer in the 2026 congressional elections is skewing toward the Democrats. Many voters are still fuming over octogenarian Joe Biden's decision to seek re-election even though his age-related deficiencies were exposed by the campaign. Several aging senators have stepped aside, and when 77-year-old Maine Gov. Janet Mills announced her candidacy for Senate this week, she made a point of vowing to serve only one term if elected.

Moulton acknowledged Wednesday that "Senator Markey and I agree on a lot of the issues." But with Markey showing none of the signs of age-related impairment that plagued Biden, will the generation gap be enough to unseat the incumbent?

Moulton has several things going for him beyond youth and vitality.

His willingness to challenge his own party's status quo, from his unseating of longtime incumbent John Tierney in 2014 through his 2017 effort to unseat Nancy Pelosi and his post-election comments last fall claiming Democrats were insufficiently sensitive to voter concerns about gender issues, lends this challenge authenticity. And he will benefit from the likely flood of voters in the Sixth District who will turn out for what's sure to be a contested race for Moulton's House seat.

But there's a flip side to some of that.

Moulton's Pelosi challenge angered some women; his comments on boys playing girls' sports ticked off some LGBTQ activists. And one by-product of Markey's half-century career in elective politics is that he has lots of friends.

Still, at a moment when Trump skeptics are eager to see like-minded political leaders pushing back as hard as possible, Moulton will surely get a hearing. Making change, he said, is "going to require stepping on some toes," but added, "That's okay, we need that right now."

Keller: Seth Moulton running against Ed Markey in Massachusetts Senate race is all about age