Rep. Lee Zeldin (R-Shirley) has surged to a 21 percentage point lead over Democratic challenger Anna Throne-Holst in a new Newsday/Siena College poll released Thursday.

The poll of 607 likely 1st Congressional District voters showed Zeldin holding a 57 percent to 36 percent lead over Throne-Holst of Sag Harbor, a former town of Southampton supervisor. That’s a six percentage point jump for Zeldin since the last Newsday/Siena poll in this race released four weeks ago. Six percent of voters are undecided.

“Every indicator is that Lee Zeldin is in a commanding position to win re-election,” said Steven Greenberg, pollster with Siena College.

Support for Republican presidential nominee Donald Trump in the Eastern Long Island district has also jumped compared to the earlier poll. Trump now holds a 51 percent to 38 percent lead over Democrat Hillary Clinton — a 10 percentage point increase.

The polls margin of error is plus or minus 4 percent. It was conducted Oct. 27 to Oct. 31.

On Oct. 28, FBI Director James Comey sent a letter to Congress announcing additional emails had been found that could be relevant to the closed investigation into Clinton’s handling of emails on a private server. The announcement set off a wave of negative headlines for Clinton.

advertisement | advertise on newsday

Throne-Holst’s main message has focused on criticizing Zeldin for continuing to support Trump since the release of a 2005 tape in which Trump brags about groping women.

“Tying Zeldin to Trump, when Trump is in the lead — I’m not sure that makes a whole lot of sense,” Greenberg said. “That’s not a winning strategy.”

Throne-Holst campaign manager Andrew Grunwald said the campaign’s internal polling shows the race is tighter. “It is clear on the ground that this is a very close race,” he said. Pointing to recent newspaper endorsements, he said, “there is no doubt that the momentum is with Anna’s campaign, and voters will hold Lee Zeldin accountable.”

Zeldin spokeswoman Jennifer DiSiena said momentum is behind Zeldin’s first re-election bid. “Voters are clearly seeing through our opponent’s despicable tactics, and rejecting her completely negative and untruthful campaign, which is flailing for good reason,” she said in a statement. “Congressman Zeldin has worked tirelessly over the past 21 months in office.”

According to the poll, Throne-Holst has lost ground with female voters and Democrats since the last survey, Greenberg noted.

Zeldin increased his lead among women by 11 percentage points, now ahead 55 percent to 39 percent.

Throne-Holst has the support from 73 percent of Democrats surveyed, while Zeldin has support from 90 percent of Republicans.

Zeldin is winning independents and other party voters 54 percent to 36 percent.

More voters view Throne-Holst unfavorably than favorably — 38 percent to 31 percent. That’s a flip from the earlier poll, when 32 percent viewed her favorably and 25 percent unfavorably.

Thirty percent of voters in the most recent poll still say they don’t know or have no opinion of her, a decrease from 43 percent in the previous poll.

advertisement | advertise on newsday

In the presidential race, Trump is dominating among voters with less than a college degree, 63 percent to 27 percent. Clinton is winning those with a college degree 47 percent to 41 percent.

Clinton like Throne-Holst is struggling to retain Democratic voters. Clinton has the support of 71 percent of Democrats, while Trump has the support of 84 percent of Republicans.

Trump is also beating Clinton with female voters in the district, leading 48 to 42 percent, according to the poll.

One Democrat doing well in the district is U.S. Sen. Charles Schumer, who leads Republican Wendy Long 57 percent to 36 percent.

“Voters on the East End of Long Island are tilting heavily toward Republicans, with the one Democratic island known as Schumer Island,” Greenberg said.

advertisement | advertise on newsday

Peter McPhee, a 69-year-old retired Verizon worker in Selden and Conservative Party member, is supporting Zeldin. “He votes for and espouses the principals I believe,” he said. He doesn’t know much about Throne-Holst, but said her support of Clinton should be disqualifying.

Tasha Greenberg, 75 of Miller Place, is supporting Throne-Holst. She said she’s “horrified” about Zeldin’s record, citing his votes to defund Planned Parenthood and opposition to a bill to prevent those on terrorism watch lists from purchasing firearms. “I would’ve thought that would get bipartisan support,” she said.