ALBANY — The federal corruption case against Republican Nassau County Executive Edward Mangano, and GOP presidential nominee Donald Trump’s slide in the polls, are working against Republicans trying to hold the State Senate majority, experts said Friday.

“There are several competitive, hotly contested races in Nassau and this certainly doesn’t help Senate Republicans,” said Steven Greenberg of the Siena Polling Institute. “It’s too early to say if it will hurt . . . but it certainly won’t move voters to the Republicans.”

“They are at risk,” agreed political scientist Gerald Benjamin of SUNY New Paltz.

Senate Republicans are already burdened by a 2-1 voter enrollment disadvantage statewide. Now they face a potential big voter turnout for Democratic presidential candidate Hillary Clinton of New York as Trump’s popularity falls in the polls after several controversies in recent weeks. The October surprise from federal prosecutors in the Mangano case on Thursday compounds all of that, they said.

“They are going to lose seats,” Benjamin said. “The question is whether they are going to lose enough seats to keep a coalition together to hold the majority.”

Some Senate Republicans on Thursday immediately called for Mangano and Oyster Bay Town Supervisor John Venditto, who was also charged, to resign. Sens. Carl Marcellino (R-Syosset) and Kemp Hannon (R-Garden City), and GOP Senate candidates Christopher McGrath of Hewlett and Elaine Phillips of Flower Hill called for the resignations.

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Senate Republican spokesman Scott Reif said Friday that the GOP candidates will continue to focus on their state accomplishments to gain seats to strengthen their slim majority. Reif said the accomplishments include record school aid increases, a 2 percent cap on the growth of property taxes, and a middle-class tax cut. Senate Republicans have also voted to strip the public pensions of officials convicted of corruption.

Republicans are betting those issues resonate more with voters than Trump or Mangano.

Senate Democratic conference spokesman Mike Murphy said on Friday, however: “With Trump at the top of the ticket and the Long Island Senate GOP candidates standing behind him, even after his offensive and dangerous rhetoric, and the Nassau Republican machine now proving our point that the GOP have become nothing but a cesspool of corruption, the people of Long Island are demanding real change.”

Democrats have been running TV and mail campaigns against Republican incumbents making corruption in Albany a top issue after former Senate Majority Leader Dean Skelos (R-Rockville Centre) was convicted of corruption charges in December.

Senate Republicans also have been campaigning in part on what they say is their role to fight corruption in a state government otherwise controlled by Democrats.

“We have zero tolerance for corruption, regardless of whether it is committed by a Democrat or a Republican,” Reif said. “Over the next few weeks, we are going to remind people of the comprehensive ethics reforms we have already achieved, and that we are committed to doing more to ensure citizens have faith and trust in their government at every level.”

Senate rules require 32 votes to pass legislation. There are 31 Republicans and a conservative Democrat who sits with the GOP conference to form the majority, which has run the Senate for most of the last 50 years. That conservative Democrat, Sen. Simcha Felder of Brooklyn, has said he will sit with either party that is in the majority to help bring the most aid to his poor district. There are 26 mainline Democrats and five Democrats in the separate Independent Democratic Conference, which pledges to remain an independent and likely pivotal conference.