The House’s seven impeachment managers, who will begin making their case for Trump’s removal on the Senate floor on Wednesday afternoon, said the president’s trial brief “confirms that his misconduct is indefensible.”

Trump’s lawyers contended in their own trial brief that even if House Democrats’ allegations are interpreted as facts, the president’s conduct is not impeachable. Their arguments suggested that an impeachable offense must be a statutory crime, noting that House Democrats’ impeachment articles — abuse of power and obstruction of Congress — did not explicitly accuse the president of committing a crime.

It’s a position that is sharply outside of the mainstream understanding among legal scholars of the “high crimes and misdemeanors” outlined in the Constitution. The initial impeachment processes against Richard Nixon and Bill Clinton included charges of “abuse of power” that leveled no statutory offenses — though Nixon resigned before he was impeached, and the House voted against charging Clinton with abuse of power.

In their reply brief, the final written argument before the beginning of proceedings on the Senate floor, the impeachment managers — led by House Intelligence Committee Chairman Adam Schiff (D-Calif.) — emphasized that the bulk of Trump’s defense was an attack on the procedures the House used that led to last month’s impeachment vote. That attack, they argued, is both baseless and an attempt to distract from Trump’s effort to pressure Ukraine to investigate his political rivals — the allegation that forms the basis of the impeachment articles.

“It is clear from his response that President Trump would rather discuss anything other than what he actually did,” the managers wrote, adding: “The Senate should swiftly reject President Trump’s bluster and evasion, which amount to the frightening assertion that he may commit whatever misconduct he wishes, at whatever cost to the Nation, and then hide his actions from the representatives of the American people without repercussion.”

The Democrats’ final argument came just hours after they raised questions about whether Trump’s lead impeachment lawyer, White House counsel Pat Cipollone, was a central witness to many of the facts of the case against Trump, and might face ethical conflicts.

"You may be a material witness to the charges against President Trump, even though you are also his advocate," the House's seven impeachment managers wrote in a letter to Cipollone, demanding that he disclose any firsthand evidence.

The Democrats say Cipollone was a routine presence in many of the episodes at the heart of allegations that Trump pressured Ukraine to investigate his Democratic rivals. For example, they say, Cipollone supervises John Eisenberg, the lead White House national security lawyer who was identified by several witnesses in the Ukraine episode as someone with knowledge of the case.

"Mr. Eisenberg appears to have informed you of at least some, if not all, of these incidents," Democrats say.

It's the House's first volley in what could become a brutal fight over the mechanics of the Trump impeachment trial, whose rules are expected to be finalized Tuesday evening.

Senate Majority Leader Mitch McConnell, for example, has proposed delaying the receipt of any of the House's evidence until after several days of opening argument — a sharp break from the 1999 Clinton trial that he said he intended to replicate.

This raises the prospect that Democrats could face challenges from Republican senators when they reference evidence that isn't officially in the Senate's record.