WASHINGTON — President Biden’s hand-picked federal prosecutor in DC confirmed to Congress last week that he wouldn’t partner with his Delaware counterpart to bring tax charges against first son Hunter Biden — arguing such cooperation rarely happens because “there is no way” to “get up to speed on everything.”

Matthew Graves made the excuse to the House Judiciary Committee in an Oct. 3 deposition that broadly confirmed the claims of two IRS whistleblowers who said in dramatic public testimony this summer that Biden appointees in the Justice Department nearly scuttled charges against the president’s child.

“The challenge is — particularly when you’re talking about US attorney and US attorney — is you’re bringing in another chain of command. And once you’re partnered, you have to reach consensus,” Graves told investigators, according to a transcript reviewed by The Post.

“So, as a manager, in general, we don’t want to do that,” Graves went on.

“And on our end of it, if it’s an ongoing investigation, there is no way, whether it’s three weeks, three months, if it’s been a multi-year investigation, that we can get up to speed on everything that has occurred beforehand. So you’re kind of buying a mansion without an inspection, and whatever problems exist, you are buying those.”

Graves said that his deputies expressed to Delaware US Attorney David Weiss’ team a willingness to facilitate a prosecution of Hunter Biden on tax fraud charges, but claimed that he only had a single 10-minute phone call with Weiss in February or March of last year — before that decision was reached — and didn’t speak with him again.

Weiss, who was elevated to the rank of special counsel in August so he could refile tax charges outside his district following the July collapse of a probation-only plea deal with the first son, called Graves to request help bringing the charges in DC.

About three weeks after that phone call, Graves said his office declined to partner following a review of case material covering allegations that Hunter Biden, while his father was vice president, failed to pay taxes on income from employers in places like Ukraine while living in DC.

“My understanding at a high level is, there was some interaction with the [assistant US attorneys] in Delaware. They got some case-related or investigation-related material. I don’t know specifically who the individuals were that they interacted with or what materials they reviewed or gathered,” Graves said.

“To the best of my recollection, no, I didn’t review any underlying case materials,” he added.

Graves said that he wouldn’t have refused to help Weiss if he sought to move forward with a case in DC, but that he was unclear what Weiss perceived about the path forward because they didn’t speak again.

“I think the best way of characterizing the decision was, we instructed — I instructed to say that we weren’t going to pursue being a local counsel on the case,” Graves said.

“Could I have told him, ‘No, we’re not going to support you, I’m not going to make my grand jury available’? I mean, I never considered it, but I guess I could’ve told him ‘no.'”

Another Biden-appointed US attorney, Martin Estrada of Los Angeles, was accused by IRS whistleblowers of blocking tax charges against Hunter Biden, resulting in the since-collapsed probation-only deal for allegedly evading more than $2 million in federal taxes from 2014-2019.

Some charges in DC may have lapsed due to statutes of limitation.

Under questioning, Graves defended the truthfulness of Attorney General Merrick Garland, who told Congress twice under oath that Weiss had the authority to charge Hunter Biden outside of his district — before IRS agents Gary Shapley and Joseph Ziegler, who worked on the case, contradicted him.

The vetting of the whistleblower allegations come amid a House impeachment inquiry into whether President Biden corruptly misused his office while vice president to aide his relatives’ foreign business interests in countries such as China, Russia and Ukraine.

Shapley and Ziegler laid out a broad alleged coverup in their own testimony to Congress, saying that career DOJ attorneys in Weiss’ office blocked them from taking various investigative steps, including by tipping off Hunter Biden to a planned search and an interview approach.

The whistleblowers also said that they were barred from investigating President Biden’s alleged role in his son and brother James Biden’s dealings, even when communications directly implicated him.

When pressed on what authority Weiss had to bring charges outside his district, Graves said, “as I understand the letters and the public reporting, he was given assurance by the attorney general, who heads our department, that he is going to be able to bring whatever charges wherever he wants to bring charges that he thinks are appropriate.”

“So, I mean, I can — this has never happened, but I can make all kinds of determinations I want to make on my own. If the deputy attorney general or the attorney general calls me up and says, ‘You are going to do the opposite of what you said,’ I am going to do the opposite of what I said. That’s the way the department works,” Graves added.

Garland’s defenders say that his contested congressional testimony has been rendered moot by his decision to make Weiss a special counsel. Republicans say, however, that Garland appears to have lied under oath — committing a federal crime.

Although Weiss was widely understood to have required special counsel or slightly different special-attorney status to bring charges outside Delaware — which would have required a sign-off from Justice Department tax attorneys and either the attorney general or deputy attorney general — Graves claimed that in theory, he could have brought a case through other methods.

“What one could do, right, if you wanted to proceed is, he could ask to have all of his trial team designated as special assistant United States attorneys in DC, and they would be designated as such, and —” Graves began.

“And did you tell him you were willing to do that?” a committee rep pressed.

“Never — that never came up. But they would be designated as such, and then a grand jury indictment would be returned under my name,” Graves offered.

Graves also said that it was unusual for Weiss’ office to have sought permission from the Justice Department’s Tax Division to bring the charges against the first son, saying it was “fairly normal” for prosecutors to initiate their own case without approval.

Prosecutors in that division had argued against charging Hunter Biden during a June 15, 2022, meeting, according to three IRS officials who previously testified to House committees.

A month earlier, members of the Tax Division had also met with Hunter’s defense attorneys, who reportedly expressed reservations to prosecutors about moving forward with the case given its political implications, according to Politico.

Weiss has yet to file federal tax charges against Hunter Biden outside of Delaware, but in September filed three felony counts related to illegal gun possession in the First State.