As Congressman Tom Suozzi and a Nassau County legislator, Mazi Pilip, make last-minute pitches, Democrats are leading in the early voting in Tuesday’s special election to fill Congressman George Santos’s vacant seat, leaving Republicans to make up the difference on a day when a snowstorm is expected to rock the region.

A senior advisor at TargetSmart who is a Democratic strategist, Tom Bonier, reports that Democrats are leading in the early-voting returns in the special election at New York’s Third Congressional District, by 11 points in early in-person voting and by 29 points in early mail-in voting.

While changes in voting habits during the pandemic and President Trump’s attacks on voting by mail have shifted Democrats toward and Republicans away from early voting, early-voting patterns have been in flux over the past few years and have become an unreliable indicator. Yet it is clear that Republicans will need to turn out to vote during tomorrow’s expected snowstorm.

The National Weather Service predicts rain overnight that will turn to snow as temperatures drop Tuesday morning. Between five and nine inches of snow is expected to fall across much of Nassau County, which accounts for much of the Third District, through Tuesday evening, alongside wind gusts of up to 40 miles an hour.

The election day snow storm will be a final twist in a race where both parties have invested significant resources, and both candidates have leaned on national parties.

The race will be a test for Democrats in the New York suburbs, a key battleground in the House, and also allow the parties to take the temperature of the national political environment going into the 2024 elections.

In 2020, the Democratic candidate, Mr. Suozzi, won re-election by more than 10 points. In 2022, Mr. Santos defeated the Democratic nominee, Robert Zimmerman, by nine points.

While Mr. Suozzi has led Ms. Pilip in every poll conducted in the race, the latest Siena College and Newsday poll has Mr. Suozzi leading Ms. Pilip by four points. The margin will also be worth watching as well.

The founder of the handicapping site Race to the WH, Logan Phillips, tells the Sun, “If Suozzi gets a big win here — six points or higher — that’s going to be a good sign for Democrats.”

“In 2022, Democrats were winning special elections by wide margins,” Mr. Phillips says. “If we took that into account, as my forecast did, it was a sign that Democrats had the chance to make the House a lot closer than some folks expected.”

Mr. Phillips’s official projection has Mr. Suozzi winning by nearly seven points, citing his history of victory in the district, his consistent polling advantage, and his more than three-to-one fundraising advantage.

Mr. Phillips did note, though, that special elections can be unpredictable and that he gives Ms. Pilip about a one-in-four chance of winning.

The election will also be the test of each party’s message on immigration, an issue that has risen to the top of voters’ minds amid record encounters between ports of entry at the southern border and New York City struggling to house migrants bused to the city by Republican governors.

On immigration, Mr. Suozzi has tacked to the right, supporting a recent proposal in the Senate, which ultimately failed, that would have coupled border security funding with a foreign aid package to Israel and Ukraine. Ms. Pilip opposed the measure.

Ms. Pilip has leaned on the county and national party in an attempt to associate Mr. Suozzi with President Biden and claim that Mr. Suozzi, who served three terms in the House, is responsible for the situation at the southern border.

Battling messages on everything from immigration to abortion have also dominated the airwaves in the expensive suburban New York advertising market, with parties spending collectively about $20 million on the race.

Aside from insights that the election results will provide into the political environment in New York City’s suburbs, the results could also have practical implications for governance over the next year.

A Democratic victory will mean an even slimmer Republican margin of control at a time when Republicans are already struggling to govern with their current House majority. Last week, a vote to impeach the homeland security secretary, Alejandro Mayorkas, failed after one more Democrat than expected showed up to vote. 

An extra seat for the Democrats could potentially make it difficult for Republicans to find times when they can successfully vote on measures, given expected absences from Congress over the next year.