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House Democrats on Saturday released their argument for why President Donald Trump should be removed from office by the Senate in the upcoming impeachment trial, calling on the chamber to “eliminate the threat that the President poses to America’s national security.”

The House impeachment managers filed to the Senate their trial brief, a summary explaining why the House passed two articles of impeachment last month charging Trump with abuse of power and obstruction of Congress, ahead of the trial arguments kicking off next week.

“President Trump’s conduct is the Framers’ worst nightmare,” the managers wrote in the brief.

The House managers made their case directly to the senators who will act as jurors in the impeachment trial.

“History will judge each Senator’s willingness to rise above partisan differences, view the facts honestly, and defend the Constitution,” the managers wrote. “The outcome of these proceedings will determine whether generations to come will enjoy a safe and secure democracy in which the President is not a king, and in which no one, particularly the President, is above the law.”

The brief is the first of multiple filings that both the House and the President’s lawyers will submit in the coming days ahead of the substantive start of the trial on Tuesday. The President’s response to the articles of impeachment, which is separate from the response to the trial brief itself, was released Saturday evening.

The legal filings represent the paper version of the arguments that will play out on the Senate floor starting next week, previewing the proceedings in the chamber that’s being transformed from legislative body to courtroom. Supreme Court Chief Justice John Roberts is presiding over the proceedings, and the Senate is being adjusted for the trial, including adding the ability to play audio and video, normally forbidden in the chamber.

House Democrats charge that Trump abused his office by withholding $400 million in security aid and a White House meeting from Ukraine while pressuring Kiev to open investigations into the President’s political rivals. Then, they say, he obstructed the congressional investigation of his misconduct with an unprecedented blockade of House subpoenas to Trump administration agencies and officials.

“The case against the President of the United States is simple, the facts are indisputable, and the evidence is overwhelming: President Trump abused the power of his office to solicit foreign interference in our elections for his own personal political gain, thereby jeopardizing our national security, the integrity of our elections, and our democracy,” the managers wrote.

The President’s legal team filed a response Saturday evening charging that the impeachment articles are “constitutionally invalid on their face.”

“The articles of impeachment submitted by House Democrats are a dangerous attack on the right of the American people to freely choose their president,” the President’s lawyers wrote in a preview of the defense they will argue on the Senate floor.

The President’s response mirrored the House Republican defense made during the impeachment inquiry, arguing that abuse of power was not a crime and the President did nothing wrong because Ukraine received the aid money and didn’t start the investigation.

The House will formally respond to the President’s response on Monday, but a Democratic aide previewed the response, saying Trump was offering “slogans” and “didn’t engage with the facts” or the mountain of evidence showing a broad campaign to pressure Ukraine to investigate the President’s political rivals while the President broke the law by withholding US aid.

House managers cite Parnas docs, watchdog report

The House’s brief for the upcoming Senate impeachment trial includes some references – but not an extensive discussion – of new evidence that’s come out since the House impeached the President last month.

The brief includes several references to the Government Accountability Office report released this week that concluded the White House violated the law by withholding the Ukraine security assistance that had been appropriated by Congress, as well as one reference to the new documents provided by indicted Rudy Giuliani associate Lev Parnas.

The House also noted in the brief that former national security adviser John Bolton, who refused to testify before the House, has said he’s willing to testify in the Senate if subpoenaed, saying his testimony would be “illuminating.”

The inclusion of the new material signals that the House managers don’t intend to solely keep their arguments to what they knew when the House passed two articles of impeachment against the President last month, and they will incorporate the new developments.

The House managers wrote in their brief that the GAO “has determined that the President’s hold was illegal and violated the Impoundment Control Act, which limits the President’s authority to withhold funds that Congress has appropriated.”

The House’s trial brief includes a single reference to Parnas, who provided the House Intelligence Committee last weekend with a trove of materials, some of which the committee has released publicly ahead of the Senate trial.

In the brief, there’s one reference to the Parnas documents – a letter that Giuliani sent requesting a meeting with then-Ukraine President-elect Volodymyr Zelensky. The House does not cite other material that Parnas provided, including text messages he exchanged with Giuliani, Rep. Devin Nunes’ aide Derek Harvey and Robert Hyde, a Connecticut congressional candidate whose texts suggests he may have been involved in an effort to surveil former US Ambassador to Ukraine Marie Yovanovitch. He’s denied there was actual surveillance of Yovanovitch.

The House also made note of Bolton’s offer to testify in the Senate in several footnotes, nothing that while he “has not cooperated with the House’s inquiry, he has offered to testify to the Senate if subpoenaed.”

“Ambassador Bolton’s testimony would likewise be illuminating in this regard given public reporting of his repeated, yet unsuccessful, efforts to convince the President to lift the hold,” the managers wrote when referencing the documents that have been withheld from Congress related to the hold on US security aid.

Senate to debate trial rules on Tuesday

The Senate will return Tuesday by passing a resolution outlining the rules of the impeachment trial, which is expected to be approved only with Republican votes.

The text of the resolution has not been released. But it’s expected to punt the question of calling witnesses until after opening arguments and senators’ questions, while including an opportunity to vote on whether the Senate should have witnesses. Senate GOP leaders are also considering condensing the number of days for opening arguments, according to sources familiar with the matter, splitting the 24 hours given to each side into two, 12-hour days instead of four, six-hour days that were used during President Bill Clinton’s impeachment trial.

House Democratic aides said they would be watching for any deviation from the Clinton precedent, as Senate Majority Leader Mitch McConnell has said he’s following, including the number of days for arguments. By shortening the number of days for arguments, it helps Senate Republicans speed up the trial with the President’s State of the Union address looming on February 4.

A Senate GOP aide argued that Senate Republicans have “every right to make this shorter rather than longer.

“There are only two counts and not exactly a mountain of evidence. Certainly, not the evidence that was compiled in Watergate and ’98,” the aide said.

But a Democratic aide said that condensing the number of days for arguments was “part of an effort to rush a rigged trial and bury the evidence.”

The fight over logistics of the trial is just an opener for the larger fight over whether there will be witnesses in the trial. Senate Democrats have called for four witnesses, including former national security adviser John Bolton and acting Chief of Staff Mick Mulvaney, and they’ve pointed to the new documents provided to the House by indicted Rudy Giuliani associate Lev Parnas as evidence the trial should have witnesses and additional documents.

A source involved in discussions said that the Senate is expected to have at least one closed session Tuesday while senators debate the rules. When that happens, everyone has to leave the chamber, including the House managers and the President’s defense team, the source said. The Senate goes into closed session during the impeachment trial because senators are jurors and are not allowed to speak during the trial.

The seven House impeachment managers, led by House Intelligence Chairman Adam Schiff, are returning to Washington Sunday to prepare for the trial, according to Democratic aides. The managers will do a walk-through of the Senate chamber on Monday.

The aides said much of the paperwork, arguments and other materials for the trial have already been drafted by staff who have been working on the preparations over the past month. They plan to continue to “refine it” over the weekend, one of the sources said.

The President’s legal team will respond to the House’s brief by 12 p.m., ET Monday. The House will then have the chance to counter to the President’s trial brief by 12 p.m., ET on Tuesday. Separately, the House has a deadline of 12 p.m., ET on Monday to respond to the President’s answer to the impeachment articles that’s due Saturday evening.

CNN’s Ted Barrett, Manu Raju, Sarah Westwood and Dana Bash contributed to this report.