Andrew Cuomo, the governor of New York who was found by the state’s top prosecutor to have violated the law by sexually harassing 11 women, continued to brave the storm on Wednesday while political support crumbled around him and moves for impeachment gathered pace.

The third-term Democratic governor – the longest-serving chief executive of any state in the nation – showed no sign of capitulating in the face of almost universal calls for his resignation from the Democratic establishment after the state’s top prosecutor released the results of the five-month investigation this week. Demands for him to stand aside poured in from individuals and institutions that had formed the bedrock of his empire.

Among former supporters now abandoning Cuomo, Democratic lawmakers in the state assembly attracted most attention as they will determine the likelihood and outcome of any impeachment. Until the New York attorney general Letitia James released her devastating 168-page report on Tuesday, finding that Cuomo had “sexually harassed current and former New York state employees”, key assembly players had guarded their positions.

But following soundings among the Democratic group, Carl Heastie, the speaker of the assembly, finally broke ranks. “It is abundantly clear to me that the governor has lost the confidence of the assembly Democratic majority and that he can no longer remain in office,” he said.

Heastie promised to move “expeditiously” to hold an impeachment investigation based on the 179 witnesses and 74,000 items of evidence gathered in the attorney general’s probe. But he has yet to specify a timeframe for impeachment charges to be drawn up or any trial staged.

As cogs of impeachment began to turn, several other critical pillars of Cuomo’s base collapsed. In addition to the top Democrats in the nation led by Joe Biden and Nancy Pelosi – both of whom have been longstanding friends of Cuomo – every Democratic member of Congress from New York has now cut ties.

On Wednesday, several trade unions that been among Cuomo’s main advocates similarly bailed out, as did another central supporter, the sexual and reproductive health provider Planned Parenthood.

As a further threat, criminal prosecutors were also beginning to circle overhead. The lead prosecutor in the state capital Albany has opened an investigation into Cuomo’s behavior based on the findings of the official inquiry, and similar moves have been made by district attorneys in Manhattan and Westchester county.

Investigators will have to take on board a three-year statute of limitations for sexual harassment cases under New York state law. However, the attorney general’s report found that Cuomo had created a hostile working environment, and that would allow prosecutors to explore incidents going back through the governor’s entire career.

Despite the seemingly impossible odds stacking up against him, Cuomo remained silent on Wednesday, allowing the statement he made hours after James’s report was published to make his case. In it, the governor followed a standard playbook of numerous powerful men accused of sexual misconduct before him – off-loading blame onto his female accusers, his political enemies, and even “generational” and “cultural perspectives” that he hadn’t “fully appreciated”.

He also included more than 40 photos of prominent politicians hugging people in an attempt to pass off his own actions as innocent. The images included former presidents George Bush and Barack Obama comforting hurricane victims.

“The facts are much different to what has been portrayed. I am 63 years old. I have lived my entire adult life in public service. That is just not who I am or who I ever have been,’ he said.

In making his calculations about whether and for how long to hold out, Cuomo might be counting on appealing directly to New York voters over the heads of his erstwhile Democratic allies. But a Marist poll on Wednesday carried a mixed message for what that could mean for him.

While it indicated that 59% of all New Yorkers thought the governor should resign, that proportion fell to 52% of registered Democratic voters – a much more nuanced result than the wall-to-wall calls for resignation coming from the party’s political leaders.

On the other hand, Cuomo cannot draw comfort from the poll’s finding that Democratic New Yorkers overwhelmingly think he should forego running for a fourth term in the gubernatorial election next year. Just 18% thought he deserved re-election.

The explosive reaction to the attorney general’s report has placed Cuomo in an ignominious position. Not only is he waging a one-man battle to undermine and discredit the gains made by the #MeToo movement in taking women’s accounts of sexual harassment seriously, but he now also runs the risk of becoming only the second New York governor to be impeached and removed from office. (The first was William Sulzer – impeached and convicted in 1913 for campaign finance violations and perjury.)

Should impeachment go ahead, it would follow on broadly the same lines as the two impeachments of Donald Trump during his presidency. Articles of impeachment – effective charges – would go to a vote in the assembly and if passed would then be put before the state senate where members and judges from the New York court of appeals would act as jurors.

A two-thirds majority vote would be needed to convict and expel Cuomo from the executive mansion.

Should he be removed, he would be replaced as governor by the current lieutenant governor Kathy Hochul. She would become the first woman to act as New York’s chief executive since the first governor George Clinton was elected 244 years ago.