Cuomo defeated a bid for the endorsement by Fordham University law professor Zephyr Teachout following an impassioned floor fight between his supporters and critics that gave vent to liberal frustrations with Cuomo over his support for business-friendly tax cuts and charter schools. The final vote was 59 percent for Cuomo to 41 percent for Teachout.
The governor did not appear at the convention but spoke to delegates over the phone. He promised to support liberal priorities including a minimum wage hike, the decriminalization of small amounts of marijuana and public campaign financing.
"If we want to enact the progressive agenda, we need to take back the state Senate," said Cuomo, adding that his own attempts to pass liberal policies have been blocked by the Senate. "It's not that we haven't to tried, it's not that we haven't fought ... I want to do it with you, and if we come together that's exactly what will happen."
The Working Families Party, a coalition of unions and progressive groups, has emerged as a leading voice on the left, helping to elect New York City Mayor Bill de Blasio. The party endorsed Cuomo in 2010, contributing some 150,000 votes to his total. New York allows candidates to run on multiple party lines.
Cuomo is widely thought to be mulling a presidential run. Losing the support of the Working Families Party would have been a political embarrassment, and worse, would have significantly cut into Cuomo's lead over Republican candidate Rob Astorino, who won the state Conservative Party's nomination at its convention Saturday.
Cuomo's nomination was in doubt until a few hours before the vote. Cuomo got a boost from de Blasio himself, who personally vouched for Cuomo and told delegates that the governor is too powerful an ally to reject.
"I know people have strong views, passionate views," de Blasio said. "So much is at stake for New York state ... I have had many a conversation with the governor, and I believe his assurance that he supports this progressive vision and will move forward with it."
Teachout had faulted Cuomo for not doing enough to address income inequality and the influence of money in politics.
"We're seeing the worst inequality in 100 years right now, and right now, still, we (liberals) find ourselves fighting for scraps," she said.
Polls show why the endorsement was so vital to Cuomo. A recent Quinnipiac University survey gave Cuomo a 57 percent to 28 percent lead over Astorino, the Westchester County executive. If an unnamed candidate running on the Working Families Party line was included, Cuomo's lead over Astorino dropped to 37 percent versus 24 percent. The telephone poll of 1,129 voters was conducted May 14-19 and has a margin of error of plus or minus 2.9 percentage points.
In exchange for an endorsement, the Working Families Party got Cuomo to agree to work to return the state Senate to Democratic control.
The Senate is now led by a coalition of Republicans and a breakaway faction of Democrats. Under the coalition leadership, the Senate has blocked many liberal priorities, including public campaign financing, codifying federal abortion rights in state law, and the Dream Act, which would extend state financial aid to students in the country illegally.
The Senate's Republican leader, Sen. Dean Skelos, said he had "grave concerns" about what he called Cuomo's support for the "leftist agenda supported by the ultra-liberal Working Families Party."
"The voters will choose who controls the New York state Senate," he said in a statement, adding that the Working Families Party "shouldn't be holding elected officials hostage in exchange for an endorsement, legislation and (campaign) money."
Despite the nomination, Cuomo is likely to face continued liberal skepticism. He was booed by dozens of convention attendees when his name was offered for the nomination. Bradley Russell, who held a poster in which Cuomo's face was superimposed over a portrait of Napoleon Bonaparte, said he doesn't trust Cuomo.
"This man believes in tax cuts for corporations and the rich," he said. "Words from a proven liar mean nothing."
The party also nominated Attorney General Eric Schneiderman and Comptroller Thomas DiNapoli, both Democrats, for re-election. Neither men faced opposition.