Candidates face today’s primary election with nearly 1 million voters already casting a ballot

Senator Ed Markey and Representative Joe Kennedy thanked supporters across Massachusetts Monday.Globe Staff

On the eve of an unprecedented primary, masked candidates bounded around Massachusetts on Monday with their political futures at stake. They chomped on hot dogs in Worcester, danced with supporters in Brookline, or knocked doors in Springfield, each closing in on the final events of a bruising campaign.

The frenetic action belied a novel reality: Nearly one million voters have already made up their minds.

While polls open Tuesday to decide a swath of races, about 927,000 voters have already cast ballots in the Massachusetts primary, setting up possibly the busiest — and certainly, the most unusual — state party contest in three decades.

By late Monday, roughly 827,000 Democratic and 96,000 Republicans ballots had been cast, according to state data, and Secretary of State William F. Galvin said he expected between 1.2 million and 1.3 million residents alone to vote in the Democratic primary. Another 150,000 were expected in the GOP race, he said.

At that level, it would mark the highest raw number of ballots cast in a state primary since 1990, when more than 1.5 million people voted. The state, now with 4.66 million registered voters, has not seen turnout top 30 percent in a state primary since 1992.

Voters are deciding a generational fight for the Senate, a combative open-seat congressional primary, and likely the fate of three House incumbents facing intra-party challenges.

Every legislative seat is also on the ballot, with several featuring progressive challengers, and voters will have to make relatively obscure picks for Governor’s Council seats or, in some cases, county treasurer.

“I think it’s fair to say . . . that a majority of people who would be participating in tomorrow’s election, in fact, have voted,” said Galvin, who estimated that somewhere between 250,000 and 300,000 people would vote in-person Tuesday.

Ballots have been flooding in under the state’s newly expanded voting law, passed this summer to give residents more options to cast ballots amid the novel coronavirus pandemic.

That included, for the first time, allowing for universal voting by mail and seven days of early voting ahead of Tuesday’s primary, an election headlined by the Senate Democratic primary between Senator Edward J. Markey and Representative Joseph P. Kennedy III, which turned hostile in its final weeks.

The early influx of votes has already upended the campaign calendar, creating weeks of intensive advertising, phone-banking, and get-out-the-vote efforts, even if in many cases, it was confined to the relatively safer confines of the virtual world.

Monday’s scene, meanwhile, felt otherwise nostalgic. Candidates fanned out to diners, hot dog shops, and sidewalks, hoping a last eyeful of them or their campaign signs could sway those voters who’ve left their decision until election day itself.

It was a familiar, if ironic, capstone to what’s been a bizarre campaign season. Voters and candidates alike have been largely sequestered to their homes amid the COVID-19 pandemic, relegating the concept of voter contact to virtual debates, phone calls, and the persistent pinging of text messages.

In many places, it’s a referendum on many within the state’s old Democratic guard. In Western Massachusetts, Representative Richard E. Neal, the 71-year-old powerful House Ways and Means chairman, is sparring with Holyoke Mayor Alex Morse, born 26 days after Neal first won his congressional seat in 1989.

Representative Stephen Lynch, 65, is trying to fend off Robbie Goldstein, a 36-year-old infectious disease specialist, within Boston and South Shore suburbia.

And, of course, there’s Markey, 74, dueling with the 39-year-old Kennedy, a sharp-elbowed race imbued with generational, ideological, and even familial battle lines.

Markey rallied supporters outside a Brookline library, driving home the theme of racial justice and highlighting his environmental advocacy, before appearing at Dorchester’s Harambee Park.

“He’s been about Black Lives Matter since before it was cool,” state Senator Sonia Chang-Díaz said of Markey, who has opened a sizable lead according to recent polling.

No Kennedy has ever lost a race in Massachusetts.

“I’m treating tomorrow like it’s Game 7 of the World Series,” Markey told a scrum of reporters after addressing the crowd in Brookline. “There’s nothing guaranteed.”

Kennedy began the day in Western Massachusetts with Representative Linda Sánchez of California, who endorsed him, meeting voters at a Springfield restaurant and organic food store, drawing in some cases awestruck support.

“He’s our guy. He’s the man,” said Derryl “Bumpy” Gibbs, owner of Bumpy’s Natural and Organic Foods. He kept repeating that he was absolutely speechless that Kennedy had come to visit.

Two Republicans, Shiva Ayyadurai of Belmont and Kevin O’Connor of Dover, are running in their Senate primary. The Democratic nominees for Senate and every federal race are expected to have the edge in November.

Heated intra-party fights litter the ballot elsewhere. South and west of Boston, a primary for Kennedy’s seat was still bowling its way through the district, which stretches from the city’s suburbs through the southern reaches of Eastern Massachusetts.

Once a nine-way fight, the seven-Democrat primary has been roiled by a crush of money, intra-party sniping, and a sense of uncertainty. One survey released Sunday suggested the slugfest had tightened, with Jake Auchincloss, a Newton city councilor and Marine veteran, and Jesse Mermell, a progressive former Brookline selectwoman, polling at the top of the field.

Yet, a chunk of those surveyed remain undecided among a field that also features Newton City Councilor Becky Walker Grossman, City Year co-founder Alan Khazei, former Wall Street regulator Ihssane Leckey, Brookline epidemiologist Natalia Linos, and attorney Ben Sigel.

Early and mail-in voting adds uncertainty to any assessments of who is up and who is down in what has been an unpredictable campaign.

“We’ve been out nonstop for the past several days,” Mermell said Monday in Mansfield, where she gathered with a small group of supporters and her 9-year-old Chihuahua and Jack Russell terrier mix named Isabella.

Hours later, Auchincloss stood on a traffic Island in Franklin with supporters, most of them members of the International Union of Operation Engineers Local 4 from Medway. Spencer Daniszewski, 17, of Ashland, had tacked a hand-made “Honk for” placard to an Auchincloss campaign sign and held it high for passing drivers.

”I can’t vote yet,” he said. “So this is my taking part in the democratic process.”

North of Boston, two Topsfield Democrats — Angus McQuilken and Jamie Zahlaway Belsito — are challenging Representative Seth Moulton in an otherwise overlooked primary on the congressional slate.

Questions have loomed of how quickly voters will actually learn of the results come Tuesday, after New York notably endured a nightmarish wait following its adoption of mail-in voting.

Galvin, speaking Monday, said he was optimistic that results would be tallied by the morning after the election, leaving open the possibility of many candidates going to bed Tuesday without celebrating, or mourning, the election that was.

He said he also expected many of the 400,000-plus ballots mailed to voters but still considered outstanding as of Monday morning would be returned before polls close Tuesday night.

“I can’t say with certainty that it’s not going to be slower,” Galvin said. “What I can tell you is that it’s been very carefully thought through. . . . It is my hope that the results coming tomorrow night will be completed, certainly, before Wednesday morning.”

Galvin has also urged those who have filled out mail-in ballots but not yet returned them to drop them off in person, because they aren’t likely to reach clerks’ offices in time by mail. But he cautioned that voters looking to drop off their completed ballots should go to their town clerk’s office or a designated drop-off location, and not their polling place.

Mail-in ballots must arrive in clerks’ offices by 8 p.m. on Sept. 1 in order to be counted. Drop-off locations can be found on the secretary of state’s website.

Dugan Arnett, Danny McDonald, Christina Prignano, and Gal Tziperman Lotan of the Globe staff and Globe correspondent Meghan Sorensen contributed to this report.