New York City voters sent an unmistakable message to Mayor de Blasio on Wednesday as he prepared to hit the unofficial presidential campaign trail again this weekend: Don’t go!

A new Quinnipiac University poll left no doubt that the mayor’s presidential ambitions don’t sit well with his constituents, with an overwhelming 76 percent recommending he give up his White House quest and a mere 18 percent suggesting he go for it.

The opposition spanned the spectrum of party, gender, race, borough and age. In another poll last month by Marist College, the split against a de Blasio presidential run was a less-punishing 65 percent to 25 percent.

The latest rejection came as the mayor planned a fundraiser in Boston on Friday for his federal political-action committee, followed by a trip Saturday to Nevada, the third state to vote in the Democratic presidential nominating contest.

He previously visited the early-voting states of Iowa, New Hampshire and South Carolina.

“Mayor Bill de Blasio’s flirtation with a 2020 White House bid is prompting a rare moment of unity among New Yorkers. Three-quarters of them say, ‘Mr. Mayor: Don’t do it,’ ” said Quinnipiac polling analyst Mary Snow.

Voters also said by a 47-32 percent margin that it would be bad for New York City if the mayor ran — including Democrats, 43 percent to 35 percent.

De Blasio, in the sixth year of his mayoralty, continues to get poor job-approval ratings.

Only 42 percent of voters in the poll approved of his performance in office, while 44 percent gave a thumbs-down.

Approval ranged from a negative 30-64 percent on Staten Island to a positive 50-38 percent in The Bronx.

Democrats gave the mayor a positive grade by a 53-34 percent margin.

But he got flunking marks from Republicans, who disapproved of his performance 70 percent to 22 percent and by independents, 52–34 percent.

Rudy Giuliani was the last New York mayor to make a bid for the presidency. He flamed out early in the 2008 Republican nominating contests.

John Lindsay suffered the same fate when he sought the Democratic Party nomination in 1972.

The poll also found that First Lady Chirlane McCray scored a tepid popularity rating of 43 percent positive and 31 percent negative as questions swirled about the spending and results of her $250 million-a-year ThriveNYC mental-health initiative.

A politician who did much better was freshman firebrand Rep. Alexandria Ocasio-Cortez, a Bronx/Queens Democrat who scored a 51-34 percent positive rating.

Quinnipiac surveyed 1,077 city voters from March 27 through April 1. The poll has a margin of error of plus or minus 3.8 percentage points.