For nearly three decades, John Larson was practically synonymous with Connecticut's First Congressional District. Then Democratic voters decided 28 years was long enough.

Former Hartford Mayor Luke Bronin decisively defeated Larson in the Democratic primary, capturing roughly 54 percent of the vote and ending the 14-term congressman's nearly three-decade run as the party's nominee. This wasn't a squeaker. It was a flat-out rejection.

And in a few days, Massachusetts voters will confront a strikingly similar choice.

Is Massachusetts Next?

In Massachusetts' Eighth Congressional District, 71-year-old Rep. Stephen Lynch is facing 39-year-old attorney and voting-rights advocate Patrick Roath in the Sept. 1 Democratic primary. Lynch has been in Congress since 2001.

Like Larson, Lynch is emphasizing experience and seniority. Like Bronin, Roath is arguing that this political moment demands a new generation of Democratic leadership. The parallels aren't perfect, but they're difficult to ignore.

Roath has attacked what he calls the "politics of the past" and argued Democrats need more urgency confronting President Donald Trump and the MAGA movement. Lynch also has vulnerabilities Larson didn't. He was one of the few congressional Democrats to vote against the Affordable Care Act in 2010. More recently, Lynch was the only member of Massachusetts' congressional delegation to vote for the Laken Riley Act, which expanded mandatory detention requirements for some undocumented immigrants accused of crimes.

Roath, meanwhile, has secured endorsements from the Boston Teachers Union and progressive organizations across the district. Recent reporting has described the race as potentially competitive.

That would have been difficult to imagine not long ago. So was John Larson losing.

Side-by-side photos show an older man in a dark blazer speaking at a podium surrounded by news microphones, left, and a younger man in a white button-down shirt standing outdoors with his arms crossed, right.
U.S. Rep. Stephen Lynch, left, and Democratic challenger Patrick Roath, right. Roath is challenging the longtime congressman in Massachusetts’ Eighth Congressional District Democratic primary.

A Different Kind of Democrat

Bronin, 47, built his Connecticut campaign around a straightforward argument: Democrats cannot respond to an extraordinary political moment with business as usual.

"We are at a moment when our country is in crisis," Bronin told supporters after his victory. "We have a president who's out of control and we need to build a Democratic Party that's bringing a whole new energy to this fight that is clearer and bolder about what we're fighting for."

Voters listened. But Bronin's victory shouldn't simply be characterized as progressives defeating moderates. Connecticut's Working Families Party actually backed Larson and criticized Bronin's record with organized labor.

Bronin nevertheless campaigned on positions including abolishing ICE, expanding renewable energy, addressing affordability and adopting a more confrontational posture toward Trump. The lesson may be more complicated than left versus center. Democratic voters increasingly appear interested in something simpler: Who looks prepared to fight?

Red, White and Sometimes Blue

There is a particular kind of Democrat increasingly vulnerable in this environment: politicians who campaign blue but govern cautiously enough that voters struggle to identify what the party actually stands for.

As our running series calls them: red, white and sometimes blue.

Reliably Democratic when election season arrives. Proudly partisan when Trump is the subject. But sometimes cautious, incremental or willing to cross the aisle on issues where their own base expects something different.

Lynch may provide Massachusetts voters with an unusually clear test of that politics. He's a Democrat from one of America's bluest states who voted against Obamacare and, this year, joined Republicans on immigration legislation opposed by every other member of the Massachusetts congressional delegation.

But Lynch also has deep union roots, decades of constituent relationships and an argument increasingly unfashionable in Democratic politics: experience matters. Massachusetts voters will decide whether that's enough.

Black Voters Aren't Automatic Votes

The question has particular relevance in diverse urban communities in both states. Hartford has a substantial Black and Latino population. Massachusetts' Eighth District stretches from Boston neighborhoods including Dorchester through communities including Brockton, Quincy and much of the South Shore.

For generations, Black voters have been among the Democratic Party's most dependable constituencies. But dependable shouldn't mean automatic.

Black voters can overwhelmingly oppose Trump while simultaneously being dissatisfied with Democratic leadership. Those aren't contradictory positions. Fear of Republicans cannot permanently substitute for enthusiasm about Democrats.

Voters dealing with housing costs, economic inequality, immigration, struggling schools and public safety increasingly want to know not simply what Democrats oppose, but what they're prepared to fight for.

From Hartford to Boston: It Isn't Just About Age

That's what makes Bronin's victory relevant beyond Connecticut. But Massachusetts voters are about to test whether this insurgency is really about age — or something deeper.

Two longtime Massachusetts Democrats face younger challengers Sept. 1. Lynch, 71, faces the 39-year-old Roath. Meanwhile, 80-year-old Sen. Ed Markey faces 47-year-old Rep. Seth Moulton.

If this were simply a revolt against aging politicians, both incumbents should be in trouble. They aren't.

Recent polling has Markey leading Moulton by a commanding margin. Markey has spent decades building credibility with the Democratic left, most notably as co-author of the Green New Deal, and voters continue to associate him strongly with progressive causes.

That creates a fascinating contrast with the Lynch-Roath race described above.

Massachusetts voters could simultaneously decide that 25 years is too long for Lynch — and that Markey's decades in Washington aren't a reason to replace him.

If that happens, the message would be difficult to reduce to generational change.

Maybe voters aren't simply asking how old their representatives are. They're asking what they've done with the time they've had.

Connecticut has already delivered its verdict on Larson. Massachusetts votes Sept. 1.

Being against Trump may not be enough. Being a Democrat may not be enough. And being red, white and sometimes blue may not be enough anymore.

Democratic candidates running for U.S. Senate for Massachusetts Seth Moulton and incumbent Senator Edward Markey. (Jesse Costa/WBUR)