A new law allows Mass. residents to vote by mail. Here’s how that’s already changing things

On the official election calendar, Massachusetts’ state primary day is Sept. 1. But in practice, voting could begin next week.

A new law allowing every registered Massachusetts voter to cast an absentee ballot by mail promises to change not only how residents pick their preferred candidates, but when, upending the long-held political calendar that voters and campaigns have relied on for decades.

Candidates have already begun flooding televisions with ads in anticipation of the start of voting, including in the heated Senate primary between Senator Edward J. Markey and Representative Joseph P. Kennedy III. Campaigns are dialing residents as part of so-called get-out-the-vote efforts at a pace usually reserved for the final stretch of a race. Local officials are swimming in an “unprecedented” surge of requests for absentee ballots.

The sea change ostensibly takes hold Monday, when every clerk’s office in Massachusetts is supposed to receive copies of the primary ballot. Once those are in hand, local officials say they’re prepared to quickly send them out to everyone who has submitted a vote-by-mail application, copies of which began popping into 4.6 million voters’ mailboxes earlier this month, after the new law passed offering more voting options amid the coronavirus pandemic.

More than a dozen states have taken similar action to expand voting in the face of COVID-19, and just eight still require an excuse to vote absentee.

But in Massachusetts, it’s created an unrivaled scenario in the state’s long political history: Programmed for centuries to flock to poll locations on Election Day — and in recent years, during tight early-voting windows — voters may now make their choice not hours or days before polls close, but weeks.

“The Tuesday Election Day is now every day, for the next five or six weeks,” said Erin O’Brien, a professor of political science at the University of Massachusetts Boston.

How voters will ultimately react is unclear. Election experts say expanding vote-by-mail options has proven to rev up turnout in primaries, which in Massachusetts state races hasn’t topped 30 percent turnout since 1992, state data show.

Applications have poured in by the thousands to local clerk’s offices both big and small. Andy Dowd, Northborough’s town clerk and the legislative chair of the Massachusetts Town Clerks Association, said roughly 1,500 of the town’s 11,000 registered voters have already applied.

“The volume we’re seeing is unprecedented,” he said. “We want to get [the ballots] out as quickly as possible.”

Advocates, too, are encouraging people to vote as quickly as possible to avoid a surge of ballots at the deadline. “We really want voters to flatten the absentee ballot curve,” said Beth Huang, director of the Massachusetts Voter Table.

Yet, when faced with high-profile choices — the heated Senate primary tops this year’s ticket — some voters may ultimately choose to wait, their inner clocks still geared toward early September decision-making. Many may procrastinate. Some may even lose their ballot, a simple but common development, experts say, as thousands of them flow into homes.

The US Postal Service, preparing for the onslaught, began cautioning voters in May to submit any ballots at least a week before they’re due. For the Massachusetts primary, that due date is by 8 p.m. on Election Day, or hand-delivered to a clerk or designated drop-box. The state has set an Aug. 26 deadline for submitting an application for a ballot.

It also comes with a warning: Secretary of State William F. Galvin’s office is reminding voters that should they vote by mail, “there is no way to take back your ballot once it reaches the city or town hall,” spokeswoman Debra O’Malley said.

“I think a change in mindset is going to be required,” said Barry Burden, director of the Elections Research Center at University of Wisconsin-Madison. And that’s on both ends: He pointed to the experience in New York City, where a month after its primary, voters still don’t know who won, effectively stretching the election season even further.

“That’s also when problems in the voting process begin to emerge,” Burden said, as failing to sign a ballot or other simple errors can render a vote uncounted. “It can be a heart-breaking time period for a lot of voters.”

But voting by mail offers a lot of positives, election administrators say. Beyond seeing shorter lines at polling centers, residents in states where vote-by-mail has already been widely adopted have become more studious, taking time to research candidates and consult with others, all with ballot in hand.

It’s something that isn’t possible within the 45 seconds they’d otherwise spend checking off names in a high school gymnasium polling center.

“I call it an open-book, take-home exam,” said Robert Stein, a Rice University professor who has consulted with state officials on mail-in-voting, including in Massachusetts. The caveat, he said, is it often takes states at least a few years to smooth out the hiccups in the system.

Massachusetts has no such luxury, and campaigns are responding in turn. They’re pumping money into television ad campaigns weeks ahead of the primary vote. In Markey’s case, he directly tied the release of his first TV spot to the dawn of mail-in balloting.

Both Kennedy and Markey have dedicated parts of their campaign websites to directing people how to vote by mail. And when campaigns are dialing potential voters, they’re regularly asking not just who they’re voting for, but how.

“About a month a half ago we stopped calling Sept. 1 Election Day. And we started calling it the last day to vote,” said John Walsh, who’s managing Markey’s campaign.

Walsh said the campaign is expecting as many as 80 percent of primary voters to submit their ballots by mail, well above the one in four who told Suffolk University pollsters in June they planned to. Kennedy was among the state’s most vocal supporters for passing a vote-by-mail law, a pitch that’s permeated his campaign messaging.

“We’ve been able to connect with thousands about [vote by mail] in just the last few weeks,” Ebenezer Abolarin, Kennedy’s field director, said. “People just seem to appreciate someone giving them guidance on this very new situation for all of us.”

It also presents new sets of benefits and challenges. Campaigns say it will allow them to better tailor their messaging as they cull those who’ve already voted from the list of voters they’re calling.

In turn, it could drive up costs, stretching what would be an intense, two-week burst of spending on mailers, digital ads, or TV time to more than a month. That could make for hard choices the closer campaigns get to Election Day, still desperate to reach every voter they can.

It all requires a change in perspective, said Jesse Mermell, one of nine Democrats running in the Fourth Congressional District primary.

“It’s Election Month,” she said, “not Election Day.”

Matt Stout can be reached at matt.stout@globe.com. Follow him @mattpstout.