ALBANY - Sen. Bernie Sanders endorsed Zephyr Teachout for New York attorney general and Jumaane Williams for lieutenant governor ahead of Thursday's Democratic primary, but stayed out of the marquee matchup between Gov. Andrew Cuomo and Cynthia Nixon.

Sanders, the Vermont independent and 2016 presidential candidate who has become a hero to progressives, announced his New York endorsements on Monday, three days before voters will head to the polls in a rare Thursday election.

In backing Teachout and Williams, Sanders aligned himself with left-leaning, insurgent candidates without institutional support from their party.

But he declined to make a specific endorsement in the governor's race, where Nixon is courting votes from the Sanders wing of the Democratic Party in her uphill battle against Cuomo, a two-time incumbent.

More:Cuomo expands lead against Cynthia Nixon in Democratic primary: Siena poll

In a statement, Sanders pledged support for all progressive candidates but only offered specific endorsements for Teachout, who is in a four-way primary for attorney general, and Williams, the New York City councilman taking on Cuomo's running mate, Lt. Gov. Kathy Hochul.

"While we need to elect all the progressives running, I would like to offer specific endorsements to two candidates I have known for many years, who are leaders of the progressive movement in New York and who stood with us in 2016: Jumaane Wililams for lieutenant governor and Zephyr Teachout for attorney general," Sanders said in the statement.

Sanders' endorsement had been coveted by the candidates running in the primary, which often draws voters from the left-most side of the party.

Teachout is in a wide-open, four-way race for the Democratic nod for attorney general, with a Siena College poll Monday showing her running in a close third behind Rep. Sean Patrick Maloney, D-Cold Spring, Putnam County, and New York City Public Advocate Letitia James, who has the state Democratic Committee's support.

Also running is Leecia Eve, a Buffalo native and former aide to Cuomo and Hillary Clinton.

Sanders' endorsement of Teachout was not unexpected; he endorsed her unsuccessful run for Congress in 2016, when she was defeated by Rep. John Faso, R-Kinderhook, Columbia County.

More:Bernie Sanders stumps for Zephyr Teachout in New Paltz

In a statement, Teachout said she was "honored and thrilled" to have Sanders' endorsement.

“Bernie Sanders has changed what’s possible in our politics by rejecting the cynicism of the status quo and insisting on a progressive agenda that puts people first," she said.

Williams is hoping to upset Hochul and join Cuomo's ticket in the fall, painting himself as an independent-minded reformer.

Under New York election law, there are separate primaries for governor and lieutenant governor, with the winners joined as a ticket in November.

Sanders' statement, meanwhile, did not make any specific mention of either Cuomo or Nixon.

Nixon, the actor best known for her role in Sex and the City, has tried to appeal to Sanders voters, backing progressive-favored policy positions like Medicaid for All and abolishing the U.S. Immigration and Customs Enforcement.

She has the support of Our Revolution, the political-organizing group that sprang out of Sanders' 2016 primary run against Hillary Clinton.

Cuomo, on the other hand, also had been courting Sanders' support, appearing with the senator when Cuomo unveiled the Excelsior Scholarship program, which covers SUNY or CUNY tuition for income-eligible, full-time students.

He has been endorsed by Hillary Clinton, as has Hochul.

In an email, Nixon spokeswoman Lauren Hitt said Sanders' non-endorsement didn't come as a surprise, pointing to a Daily News article from April where Sanders' senior adviser Jeff Weaver said he did not anticipate the senator would weigh in.

"But we think Bernie's endorsements today of Jumaane and Zephyr are great news for our progressive slate of candidates," Hitt said. "The more young progressives come to the polls, the more likely it is that Andrew Cuomo and his slate of establishment candidates will lose."