The primary is less than a week away. For voters who got their mail-in ballot but haven’t sent it in yet, Secretary of the Commonwealth Bill Galvin says: It’s too late. He strongly suggests putting mail-in ballots in a local ballot drop box, and as a last resort voting in person on primary day.

“Do not mail the ballot. It’s too late, we can’t be sure we are going to receive it,” Galvin said. “All ballots have to be in the possession of local election officials by 8 o’clock on Tuesday night.”

Mail-in voting has grown in popularity in recent years, with nearly 50% of voters choosing to vote early from home in recent elections. And the ballots have been coming in, according to Galvin.

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“We have 273,000 Democratic ballots that have already been received back,” said Galvin. “On the Republican side, we have 73,000, which — in both cases — is higher than we were four years ago in 2022.”

But he says there are about 100,000 mail-in ballots still out there. He encourages everyone who may have a ballot kicking around to bring it to a drop box. Voters can use this webpage from Galvin’s office to find a drop box in their city or town.

Early in-person voting ends on Friday ahead of the primary on Tuesday.

Turnout is hard to predict because of all the different ways people vote now, but Galvin says higher mail-in figures so far could suggest more voter engagement than the last midterms, though it could just suggest that its the preferred way to vote.

In the state primary in 2022, just over 45% of voters who cast a ballot chose to vote by mail — compared to half who voted the day of the primary, and a small number who voted early in-person.

Election monitors from the Department of Justice will be at polling places in Boston and New Bedford for next week’s primary. Galvin says this is nothing new, and it happens all the time. Voters shouldn’t be uncomfortable because these monitors shouldn’t interact with them at all.

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“We’ve never had an issue in the past. They’ve told us where they were going, we’ve told them what we expect,” he said. “But they’ve always understood that they could observe but they can’t interfere.

Polls will be open on Tuesday from 7 a.m. to 8 p.m.