As Vice President Mike Pence hid from a marauding mob during the Jan. 6 invasion of the Capitol, an attorney for President Donald Trump emailed a top Pence aide to say that Pence had caused the violence by refusing to block certification of Trump’s election loss.

The attorney, John C. Eastman, also continued to press for Pence to act even after Trump’s supporters had trampled through the Capitol — an attack the Pence aide, Greg Jacob, had described as a “siege” in their email exchange.

“The ‘siege’ is because YOU and your boss did not do what was necessary to allow this to be aired in a public way so that the American people can see for themselves what happened,” Eastman wrote to Jacob, referring to Trump’s claims of voter fraud.

Eastman sent the email as Pence, who had been presiding in the Senate, was under guard with Jacob and other advisers in a secure area. Rioters were tearing through the Capitol complex, some of them calling for Pence to be executed.

Jacob, Pence’s chief counsel, included Eastman’s emailed remarks in a draft opinion article about Trump’s outside legal team that he wrote later in January but ultimately chose not to publish. The Washington Post obtained a copy of the draft. Jacob wrote that by sending the email at that moment, Eastman “displayed a shocking lack of awareness of how those practical implications were playing out in real time.”

Jacob’s draft article, Eastman’s emails and accounts of other previously undisclosed actions by Eastman offer new insight into the mind-sets of figures at the center of an episode that pushed American democracy to the brink. They show that Eastman’s efforts to persuade Pence to block Trump’s defeat were more extensive than has been reported previously, and that the Pence team was subjected to what Jacob at the time called “a barrage of bankrupt legal theories.”

Eastman confirmed the emails in interviews with The Post but denied that he was blaming Pence for the violence. He defended his actions, saying that Trump’s team was right to exhaust “every legal means” to challenge a result that it argued was plagued by widespread fraud and irregularities.

“Are you supposed to not do anything about that?” Eastman said.

He stood by legal advice he gave Pence to halt Congress’s certification on Jan. 6 to allow Republican state lawmakers to investigate the unfounded fraud claims, which multiple legal scholars have said Pence was not authorized to do.

Eastman said the email saying Pence’s inaction led to the violence was a response to an email in which Jacob told him that his “bull----” legal advice was why Pence’s team was “under siege,” and that Jacob had later apologized.

A person familiar with the emails said Jacob apologized for using profanity but still maintained that Eastman’s advice was “snake oil.” That person, like several others interviewed for this story, spoke on the condition of anonymity to discuss private conversations.

A Trump spokesman did not respond to a request for comment for this article.

The House select committee investigating the Jan. 6 attack has said that it plans to subpoena Eastman as it investigates his role in Trump’s efforts, which included two legal memos in which Eastman outlined how Republicans could deny Joe Biden the White House.

In the days before the attack, Eastman was working to salvage Trump’s presidency out of a “command center” in rooms at the Willard hotel near the White House, alongside such top Trump allies as Rudolph W. Giuliani.

Jacob wrote in his draft article that Eastman and Giuliani were part of a “cadre of outside lawyers” who had “spun a web of lies and disinformation” in an attempt to pressure Pence to betray his oath of office and the Constitution.

Jacob wrote that legal authorities should consider taking action against the attorneys.

“Now that the moment of immediate crisis has passed, the legal profession should dispassionately examine whether the attorneys involved should be disciplined for using their credentials to sell a stream of snake oil to the most powerful office in the world, wrapped in the guise of a lawyer’s advice,” he wrote in the draft.

Robert Costello, a lawyer for Giuliani, said Jacob had a right to his opinion. “This is an opinion piece, and not surprisingly, he agrees with his own opinion,” Costello said.

The House select committee investigating the attempted insurrection at the Capitol on Jan. 6 faces an uphill battle with former Trump administration officials. (Blair Guild/The Washington Post)

A bipartisan group of former government officials and legal figures, including two former federal judges, has asked the California bar association to investigate Eastman’s conduct.

Eastman’s memos gave several options for Pence to use the vice president’s ceremonial role of counting electoral college votes to halt Trump’s defeat. Eastman has argued that the 1887 Electoral Count Act is unconstitutional, and that the vice president has power under the 12th Amendment to decide whether electoral votes are valid.

Under the most drastic of the options outlined in the memos, Pence would have rejected electoral votes for Biden from states where Republicans were claiming fraud, making Trump the winner — a proposal that Eastman has more recently tried to disown as a “crazy” suggestion he did not endorse.

Eastman made the case for Pence to act during a meeting in the Oval Office with Trump, Pence, Jacob and Pence’s chief of staff, Marc Short, on the afternoon of Jan. 4, according to two people familiar with the discussions. The meeting was reported in the media soon after. Pence advisers said they had never heard of Eastman before January.

The meeting was called, the people said, because Trump was frustrated that Pence was not acceding to his demands, and wanted the vice president to hear arguments from Eastman, whom he viewed as having more credibility in legal circles than some of Trump’s other legal advisers.

Eastman argued that Pence should at least try the maneuver of not certifying electors on Jan. 6, because it had never been done before, and so had not been ruled on by the courts, one of the people familiar with the discussions said. Eastman told The Post he did not recall making “any such statement.”

Eastman said that, in response to a question from Pence, he said in the meeting that it was an “open question” whether Pence had the ability to unilaterally decide which electoral votes to count.

During a little-noticed radio interview that evening, Eastman said that although it would be politically impossible for a vice president to certify his “favorite slate of electors” without any evidence of fraud, the “level of corruption” in the 2020 vote could not be allowed to stand.

“I think that makes the exercise of the vice president’s power here very compelling,” Eastman said.

In a meeting the following day with Short and Jacob at the Eisenhower Executive Office Building, Eastman began by arguing that Pence should reject Biden electors, according to the two people. He did not share his memos outlining how to stop Biden’s victory with Pence’s team at either the Jan. 4 or the Jan. 5 meetings, according to the people familiar with the discussions. Eastman’s memos were first reported in the book “Peril” by Washington Post reporters Bob Woodward and Robert Costa.

Jacob wrote in his draft article that a Trump lawyer conceded to him in a Jan. 5 meeting that “not a single member of the Supreme Court would support his position,” that“230 years of historical practice were firmly against it,” and that “no reasonable person would create a rule that invested a single individual with unilateral authority to determine the validity of disputed electoral votes for President of the United States.”

The two people familiar with the matter said Eastman was the only lawyer in the Jan. 5 meeting.

By the end of the two-hour meeting, the people said, Eastman had conceded that having Pence reject Biden electors was not a good plan.

Eastman denied to The Post that he made concessions and said he never advocated for Pence to reject the electors outright. “That is false,” he said. “And distorting the conversation, which depends heavily on what scenario was being discussed.”

In telephone calls later on Jan. 5, Eastman proposed to Pence advisers that he take a less drastic option outlined in the memos of “sending it back to the states” for the unfounded fraud claims to be examined. Eastman also suggested on several occasions, according to the people with knowledge of the meetings, that Pence could intervene because the courts would invoke “the political question doctrine” and not intervene.

“But if the courts stayed out of a standoff between the Vice President and Congress over the fate of the presidency, then where would the issue be decided? In the streets?” Jacob wrote in his draft op-ed.

Eastman told The Post: “I did not push for electors to be thrown out, but for the disputes to be referred to state legislatures, as had been requested by key legislators in several states, for assessment of the impact of the acknowledged illegality in the conduct of the election.”

Around 1 p.m. on Jan. 6, as Trump addressed supporters at a rally near the White House, Pence’s office released a letter to Congress stating that he would not block the certification. Thousands of Trump supporters marched to the Capitol and rioted.

“What the lawyers did not tell the crowd — and to the best of my knowledge, never told the president — is that they were pushing an abstract legal theory that had overwhelming drawbacks and limitations,” Jacob wrote in the op ed.

Jacob wrote that Pence never considered a different course of action.

After the unrest began on Jan. 6, Jacob sent an email to memorialize his conversation with Eastman from the day before, according to the two people with knowledge.

After Pence was escorted out of the Senate, Jacob emailed Eastman to criticize the legal advice he had pushed to Pence on stopping certification.

“Thanks to your bull----, we are now under siege,” Jacob wrote, according to Eastman. Eastman, while willing to discuss the email, declined to provide a copy to The Post. One of the other people with knowledge of the matter confirmed the content of Jacob’s email.

That led to Eastman sending the email stating that Pence’s decision led to the “siege.”

The two exchanged further messages in which Jacob apologized for his expletive, but not his critiques, and Eastman said that he had wanted Pence to postpone the count to allow states to investigate, according to Eastman and the two people familiar with the exchange.

That evening, Eastman told Jacob in another email that Pence should still not certify the results, according to Eastman and one of the people familiar with the emails. That email from Eastman came after the rioters had been cleared from the Capitol and Pence had returned to the chair to preside over the proceedings and vowed to continue.

Pence allowed other lawmakers to speak before they returned to counting the votes, and said he wasn’t counting the time from his speech or the other lawmakers against the time allotted in the Electoral Count Act.

Eastman said that this prompted him to email Jacob to say that Pence should not certify the election because he had already violated the Electoral College Act, which Pence had cited as a reason that he could not send the electors back to the states.

“My point was they had already violated the electoral count act by allowing debate to extend past the allotted two hours, and by not reconvening ‘immediately’ in joint session after the vote in the objection,” Eastman told The Post. “It seemed that had already set the precedent that it was not an impediment.”

Eastman, 61, is a veteran conservative legal activist who clerked for Supreme Court Justice Clarence Thomas. A longtime member of the Federalist Society, he has spent much of his legal career fighting same-sex marriage.

He is a senior fellow at the Claremont Institute, a conservative think tank based in Upland, Calif., whose leaders stridently defended Eastman from criticism over his role in Trump’s attempt to overturn the election and attacked the media’s coverage of it.

Eastman was sharply criticized by Democrats in August last year for writing an article for Newsweek that questioned then-Sen. Kamala D. Harris’s eligibility to be vice president on the grounds that her parents were not U.S. citizens when she was born. He said his understanding was that Trump first noticed him arguing against birthright citizenship on Fox News.

Eastman has said that he first made contact with lawyers working on Trump’s election challenges during the weekend after the election in Philadelphia, where he happened to be attending an academic conference. The law firm Jones Day had just withdrawn from representing Trump and, Eastman said in a podcast interview in June, “somebody had heard I was in town and brought me over to the headquarters.”

Eastman’s visit to Trump’s team was brief, but “long enough to catch covid,” he said on the podcast hosted by David Clements, a former New Mexico State University professor who is well known in election-denial circles.

Eastman testified via video about purported fraud to Georgia state senators at a Dec. 3 hearing where Giuliani also spoke. Giuliani said state legislators were given copies of a paper by Eastman that argued they could reject election results and directly appoint electors.

Eastman’s seven-page paper featured theories about voter fraud published by the right-wing blog the Gateway Pundit and an anonymous Twitter user named “DuckDiver19,” according to a copy Eastman shared with The Post.

Eastman has said that Trump asked him to draft a brief calling for the Supreme Court to allow Trump to intervene in a case filed by Texas Attorney General Ken Paxton (R), which sought to block the electoral college votes from four states. Eastman submitted his brief on Dec. 9 and the high court rejected the case two days later.

Eastman was previously a professor of law at Chapman University in Orange, Calif. A week after the Jan. 6 attacks, Chapman President Daniele Struppa announced that Eastman had agreed to retire from the school after what Struppa called a “challenging chapter for Chapman.”

At the time of the Capitol attack, Eastman was on leave from Chapman and serving as a visiting professor at the University of Colorado, which subsequently stripped him of some of his duties there.

Tom Hamburger contributed to this report.