Secretary of State William Galvin expects a record-setting number of Massachusetts voters will take part in tomorrow's Democratic presidential primary election.

Galvin says nearly 1.9 million people may cast ballots in the Democratic and Republican primaries tomorrow. 1.5 million of them may pull Democratic ballots, enough to set a new record for Democrats.

"The unifying factor on the Democratic side is a concern about making sure that President Trump is not reelected. To that end, and to the fact that he's brought many new independents into the party to participate, I think the [Democratic] turnout tomorrow will be about 1.5 million," Galvin said.

Galvin said former Gov. Wiliam Weld's challenge to President Donald Trump may only stir up 350,000 Republican votes and likely won't eclipse 2016's 687,000 Republican ballots.

Also new this presidential cycle is early voting.

"We had never had early voting in a primary before, but we had over 190,000 Democrats cast early voting, early votes during the five days that we had early voting," Galvin said.

The state's chief elections official said voters who cast ballots for former Democratic presidential nominees Pete Buttigieg and Tom Styer during last week's early voting period knew there was a risk their candidate may not make it to election day proper.

"It's a tradeoff. We allow you to vote early, but we don't write an insurance policy on it," Galvin said.

Support for Vermont Senator Bernie Sanders and Massachusetts Senator Elizabeth Warren is fueling excitement for the race.