After nearly three years searching for grounds to ­impeach President Trump, House Democrats have landed on “bribery.” Intelligence Committee Chairman Rep. Adam Schiff (D-Calif.) cited bribery ­repeatedly as he grilled impeachment witnesses. House Speaker Nancy Pelosi, raising her finger in triumph, declared the witnesses have provided “devastating testimony” and “evidence of bribery.”

Not so fast: What the Democrats are labeling “bribery” isn’t illegal, according to the Supreme Court. And the public won’t support impeaching a president who hasn’t broken any law.

Truth is, Democrats are trying to impeach Trump for the same kind of give-and-take horse-trading that politicians do every day. They should look in the mirror.

The pretext for the bribery charge is a July 25 call between Trump and his Ukrainian counterpart, Volodymyr Zelensky. Trump asked for a “favor” — to investigate Ukrainian meddling in the 2016 US election and Joe Biden’s son’s dealings with a corrupt Ukrainian energy company. Trump didn’t say military aid ­depended on it. But aid was ­delayed, and Democrats insist a quid pro quo was implicit. Therefore, bribery.

But the law isn’t on the ­impeachers’ side. Nobody knows that better than Chief Justice John Roberts, who would preside over a Senate trial, if that occurs. Roberts crafted the Supreme Court’s 2016 unanimous ruling defining political bribery.

In that case, former Virginia Gov. Bob McDonnell and his wife had been convicted of “bribery” for accepting gifts like a Rolex watch and help paying for their daughter’s wedding from a business friend they had hosted at the governor’s mansion and ­introduced to other state officials.

The Supremes reversed these convictions, explaining that not every exchange of a favor — in this case, meetings and introductions — amounts to bribery. The McDonnells didn’t go far enough — like getting a law passed for their friend — for them to be guilty of bribery.

Roberts wrote that political self-dealing may be “distasteful” or even “tawdry.” Politics isn’t pretty. But the Supremes wanted to prevent a “boundless interpretation of the federal bribery statute” that would land virtually all politicians in jail.

Critics of the McDonnell ruling predicted it would make prosecutions impossible. And shortly after the ruling, prosecutors dropped charges against New Jersey Sen. Robert Menendez for doing big-time favors for a generous contributor.

But prosecutors were able to nail New York state Assembly Speaker Sheldon Silver in 2018. Silver accepted some $3 million from a law firm for using his official office to steer lucrative mesothelioma lawsuits to that firm. That was blatant bribery, the real deal.

Not so with Trump and Zelensky. The Ukrainian president insists he felt under no pressure to do the favor, and never did. The aid was released anyway on Sept. 11. Schiff’s witnesses cited only second- or third-hand rumors linking aid to investigations. Pure speculation, not evidence that would stand up in a court.

US Ambassador to the European Union Gordon Sondland testified that Zelensky’s invitation to the White House hinged on “investigations.” But that’s the sort of normal give and take, like invitations to the Virginia governor’s mansion, that the justices said doesn’t rise to the level of bribery. Sondland couldn’t tie the aid to “investigations.”

Trump’s July 25 request for a “favor” doesn’t meet the Supreme Court’s definition of bribery. Nor is it the kind of traitorous conduct the Framers feared when drafting the impeachment clause. They wanted to prevent a president from taking bribes or selling out America to a foreign country.

No one can accuse Trump of such traitorous bribery.

He has demanded Americans get more for their aid dollars and pressured other NATO countries to pay their fair share. Trump says he is tired of America being the “piggy-bank nation that foreign countries have been robbing and deceiving for years.”

As for the Democrats’ broad definition of bribery, it’s synonymous with politics as usual, not a crime. If they use it to impeach this president, there is nothing to stop any future House majority from impeaching a president they simply dislike. No future president could govern and remain in power if that becomes the standard.

Betsy McCaughey is a former lieutenant governor of New York.