HEMPSTEAD, N.Y. — With the might of incumbency and New York State’s Democratic machine at his back, Gov. Andrew M. Cuomo cruised to the nomination for a third term on Wednesday, as Hillary Clinton and other powerful friends touted his administration as a model for the state and, perhaps, the nation.

For Mr. Cuomo, who effectively controls the state party, the endorsement was inevitable. But the rhetoric surrounding his coronation was geared to ratchet up enthusiasm for the governor, who is dealing with an unexpectedly prickly challenge from the left from Cynthia Nixon.

And while Ms. Nixon dropped in here on Wednesday — shaking hands, doing interviews, and leaving before noon — the moment undeniably belonged to Mr. Cuomo, with an assist from Mrs. Clinton, whose support in the convention hall here at Hofstra University seemed little dimmed by her loss to Donald J. Trump in 2016.

“Now more than ever, we need leaders who will stand up for progressive values,” Mrs. Clinton said, after reeling off a laundry list of Democratic priorities, from fighting climate change to fighting for the rights of immigrants. “Most of all, we need leaders who believe in producing results and getting things done, leaders like Andrew Cuomo.”