But Conner changed course in this year’s campaign for governor, after concluding that Democrats could only win with more daring messages on issues such as public health and immigration.

A 27-year-old social worker, Conner voted for Hillary Clinton in the 2016 primaries, spurning the more liberal Senator Bernie Sanders, Independent of Vermont, whom many of her peers backed.

DETROIT — For Rachel Conner, the 2018 election season has been a moment of revelation.

And so on a recent Wednesday, she enlisted two other young women to volunteer for Abdul El-Sayed, a 33-year-old advocate of single-payer health care running an uphill race in Michigan to become the country’s first Muslim governor.


“They need to wake up and pay attention to what people actually want,” Conner said of Democratic leaders. “There are so many progressive policies that have widespread support that mainstream Democrats are not picking up on, or putting that stuff down and saying, ‘That wouldn’t really work.’”

Voters like Conner may not represent a controlling faction in the Democratic Party, at least not yet. But they are increasingly rattling primary elections around the country, and they promise to grow as a disruptive force in national elections as younger voters reject the traditional boundary lines of Democratic politics.

Energized to take on President Trump, these voters are seeking to remake their own party as a ferocious — and ferociously liberal — opposition force. Many appear as focused on forcing progressive policies into midterm debates as they are on besting Republicans.

The impact of these activists in the 2018 election has been limited but revealing: Only about a sixth of Democratic congressional nominees so far have a formal affiliation with one of several important insurgent groups.

Of the 305 candidates, 53 have been endorsed by the Justice Democrats, the Working Families Party, the Progressive Change Campaign, and Our Revolution, organizations that have helped propel challenges to Democratic incumbents.


But the voters who make up the ascending coalition on the left have had an outsize effect on the national political conversation, driving the Democrats’ internal policy debates and putting pressure on party leaders unseen in previous campaigns.

Mark Brewer, a former longtime chairman of the Michigan Democratic Party, said “progressive energy” was rippling across the state.

But Brewer, who backs Gretchen Whitmer, a former state Senate leader and the Democratic front-runner for governor, said Michigan Democrats were an ideologically diverse bunch and the party could not expect to win simply by running far to the left.

In Maryland, Democrats passed over several respected local officials to select Ben Jealous, a former NAACP president and an ally of Sanders who backs single-payer health care, as their nominee for governor.

In a climactic primary upset in New York in June, Alexandria Ocasio-Cortez, a 28-year-old Democratic socialist, felled Representative Joseph Crowley, the fourth-ranking Democrat in the House.

With about two months left in primary season, a handful of races remain where restive liberals could flout the Democratic establishment.

Beyond El-Sayed, there are also insurgents contesting primaries for governor in Florida and New York, for Senate in Delaware, and for a smattering of House seats in states including Kansas, Massachusetts and Missouri.

The pressure from a new generation of confrontational progressives has put Democrats at the precipice of a sweeping transition, away from not only the centrist ethos of the Bill Clinton years but also, perhaps, from the consensus-oriented liberalism of Barack Obama.


Less than a decade ago, Obama’s spokesman, Robert Gibbs, derided the “professional left” for making what he suggested were preposterous demands — such as pressing for “Canadian health care.”

That attitude now appears obsolete, on matters well beyond health policy. Corey Johnson, 36, the progressive speaker of the New York City Council, who supported Crowley over Ocasio-Cortez, urged Democrats to recognize the intensity of “anger, fear, and disappointment from people in our own party.”