Manhattan U.S. Attorney Preet Bharara’s office on Wednesday called for former Assembly Speaker Sheldon Silver to receive the highest sentence ever for a New York legislator — more than 14 years — for crimes that “corrupted the institution that he led for more than 20 years.”

The government also called for the 72-year-old former powerbroker to forfeit $5.1 million and pay a fine of $1 million, called probation officials’ recommendation of 10 years in prison not enough and said a term of 22 to 27 years under federal sentencing guidelines was not “unreasonable.”

“The sentence imposed on Silver should reflect the unprecedented magnitude, duration, and scope of his abuse of power,” prosecutors said. “It should reflect the immeasurable damage Silver caused to the democratic process and to the public trust.”

“There is no excuse or mitigating factor tempering the seriousness of Silver’s crimes, which were motivated by greed and accomplished through exploitation of his enormous power and his willingness to lie and deceive at every turn,” the government added.

Silver, convicted in December of doing legislative favors for an asbestos researcher and two real estate companies in return for help getting legal referral fees of nearly $4 million, is to be sentenced on May 3 by U.S. District Judge Valerie Caproni.

The judge requested a chart of federal public corruption sentences inside and outside New York. An appendix to the government filing indicates that the highest recent New York sentence, which prosecutors want Silver to top, was 14 years for former Assemb. William Boyland last year.

In his own sentencing memo filed with the judge, Silver adopted a remorseful tone. “I failed the people of New York,” he said in a letter to Caproni. “ . . . What I have done has hurt the Assembly, and New York, and my constituents terribly, and I regret that more than I can possibly express.”

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The disgraced ex-speaker’s filing also included letters from former Mayor David Dinkins and teachers union boss Randi Weingarten. His lawyers asked for leniency — less than 10 years, all or a large part served through community service — based on his public service, age and poor health.

“Mr. Silver has cared about, and fought for, all New Yorkers,” his lawyers wrote. “While Mr. Silver’s many public and private good works do not excuse the conduct on which his conviction rests, they — along with his personal circumstances — deserve thoughtful consideration in reaching a result that is truly fair.”

Both sides devoted segments of their sentencing memorandums to explosive disclosures last week that the government had evidence Silver engaged in an affair with a woman whom he helped get a job, and an affair with a high-powered lobbyist.

“Each of these abuses of power,” said prosecutors, who have not named the women, “further demonstrate Silver’s willingness to use his position to further his personal interests, rather than to act in the best interests of all of the people of his Assembly District and the State.”

But Silver’s lawyers said the allegations were unproven, had been used by the government as a tactic to keep him from offering character evidence at trial, and had constituted their own form of punishment when they were released last week.

“The punishment in the court of public opinion has simply been devastating — not only for Mr. Silver and the individuals involved, but also for the totally innocent members of Mr. Silver’s family,” said defense lawyers Joel Cohen and Steve Molo.

Silver’s wife of nearly 50 years, Rosa, did not mention the alleged affairs in her letter. “I am not sure what I can say to Your Honor except that my husband is a good man,” she wrote to Caproni.

The lawyers also repeated a point they made during Silver’s trial — that his crimes involved funding asbestos research, finding lawyers for victims, helping real estate companies get merited tax breaks, and balancing the interests of landlords and tenants in Albany legislation.

“Without trivializing the jury’s findings,” they told Caproni, “the court should consider that the people of this state did not tangibly suffer from any of the official acts Mr. Silver allegedly performed in exchange for receiving the referral fees at issue.”

Bharara’s office asked for former Senate leader Dean Skelos, also convicted of corruption last year, to get at least 12 1/2 years, slightly less than Silver.