NEW YORK (NYTIMES) - Governor Andrew Cuomo took a decisive step toward a third term on Thursday (Sept 13), quelling a threatened liberal rebellion by turning aside the insurgent challenge of Cynthia Nixon after a bruising battle to claim the Democratic nomination in New York.

Cuomo had marshalled the support of nearly all of the state's most powerful Democratic brokers - elected officials, party leaders, labor unions and wealthy real estate interests - to defeat actress and activist Nixon, 52. Nixon is known for her role as Miranda Hobbes on HBO's Sex and the City.

The race cemented Cuomo's standing as an unmatched force in New York politics and a merciless tactician with little regard for diplomacy.

Nixon had cast her first-time candidacy as a fight for the direction of the Democratic Party in New York and beyond, offering a pure brand of liberalism against Cuomo's more triangulating pragmatism, a style defined less by ideology and more by what he deemed possible.

In the end, the governor's record of achievements - on gun control, same-sex marriage, the minimum wage, paid-family leave and more - and his gargantuan fundraising advantage spoke louder than Nixon's objections over legislation he sidelined in the byzantine corridors of Albany's capital.

The undercard races for attorney general and lieutenant governor, where insurgents allied with Nixon challenged loyalists to Cuomo, were too close to call.

As Nixon's hopes faded as Primary Day neared, liberal activists had redoubled their efforts in those contests, as well as some legislative primaries, to provide a check on Cuomo's powers.

Cuomo's victory ensures that no Democratic governor or senator in America lost a party primary in 2018, a sign of how steep a climb Nixon had faced, even before the governor's campaign unloaded a sum close to US$25 million (S$34 million) to blanket the contest in a blizzard of television ads and glossy mailers.

In November, Cuomo, 60, will seek to match the three terms his father, Mario Cuomo, achieved as governor. He has forcefully denied any presidential ambitions of his own, saying the only way he would not serve through 2022 would be death.

Cuomo himself had sought to mostly ignore Nixon in recent months, focusing repeatedly on President Donald Trump.

Cuomo's campaign, meanwhile, methodically pushed to undermine Nixon's credibility in often-caustic terms, tapping into the concerns of New York Democrats that an experienced governor is needed while a hostile Republican occupies the White House.

After a six-month slog versus Nixon, Cuomo now faces a less than 60-day sprint of a general election against the Republican, Marcus J. Molinaro, the affable Dutchess County executive who was once the youngest mayor in the nation. He, like Nixon, is expected to be drastically outspent by Cuomo.

And in a heavily Democratic state in what most strategists predict will be a Democratic year, Molinaro's bid is not seen as a top-tier race for Republicans nationally.

The final margin in the primary - polls never showed the race closer than 20 percentage points - belied the ferocity of the campaign, which began with the charge that Nixon was an "unqualified lesbian" by a top surrogate for Cuomo and ended with a mailer accusing her of silence on anti-Semitism. Cuomo called it "inappropriate" but did not apologise.

"He won ugly," said Bradley Tusk, who served as campaign manager for former Mayor Michael Bloomberg.

Even before the polls had closed, there were worried whispers from New York City to Albany of those who had crossed him readying for a coming retribution tour.

When Nixon burst onto the political stage in March, it was as if she had unleashed the repressed id of New York progressives long frustrated with Cuomo's transactional ways.

But for many voters, Nixon never successfully presented enough evidence that she was prepared to be governor, other than offering what she was not: an Albany insider or Cuomo.

"If you run an outsider campaign, you have to run a campaign like Trump did, saying 'Things are so bad that you've got nothing to lose, so who cares that I don't have experience,'" Tusk said. "In this case, the guy with experience gets a lot done."

Still, in losing, Nixon arguably made as much of a policy impact on New York as some elected officials have: Cuomo embraced a series of liberal ideas soon after her entry, including moving toward legalising marijuana, extending voting rights to parolees and brokering a deal to dissolve a group of Democratic state senators who had aligned with Republicans in Albany.

While Nixon scored a record number of small donors for a New York race, she struggled to collect larger donations, pulling in a total of just under US$2.5 million with about 10 days left in the race.

That is roughly how much Cuomo raised in a single day, at his birthday fundraiser in December.

Cuomo stumbled across the finish line in the final days, dogged by questions of the timing of a bridge opening and a mailer that incorrectly sought to link Nixon to anti-Semitism.

Molinaro has used both issues to hammer Cuomo in some of the opening salvos of the fall campaign.

For now, Nixon is still technically on the November ballot as the Working Families Party nominee. She must decide whether to withdraw, and if so, the party, which spent much of the year at war with Cuomo, must decide whether to grant its line to the incumbent governor.