Washington (CNN) The Republican staff on the three panels involved in the impeachment investigation have drafted a detailed memo , circulated to GOP members of all three committees and obtained by CNN, outlining their defense of President Donald Trump.

Using witness testimony from the closed-door depositions, as well as public reporting, the memo attempts to undercut several key arguments made by Democrats outlining the alleged culpability of Trump in his actions toward Ukraine, particularly in his decision to place a hold on US security assistance to the country in exchange for investigations into his political rival.

The memo marks the most centralized and detailed effort to lay out the Republican counterargument to impeachment that has been crafted and will serve as the baseline for members to utilize in their defense of Trump as the impeachment probe moves into public hearings on Wednesday

The four central defenses, which are detailed over the course of the memo, are as follows:

"These four key points undercut the Democrat impeachment narrative that President Trump leveraged U.S. security assistance and a presidential meeting to force Ukraine to investigate the President's political rivals," the memo reads.

On Tuesday evening, Democrats released a rebuttal memo of their own. Their memo argues that the Ukrainians did feel pressure from the Trump call, they noted there were conditions placed on a White House meeting with Zelensky and that Ukrainians knew the aid had been delayed before it become public, pointing to recent testimony released as part of the impeachment inquiry.

During the July 25 phone call, Zelensky brought up US military assistance to Ukraine, which has been at the center of US policy since Russia and its proxies invaded Eastern Ukraine in 2014, telling Trump that he was interested in buying additional anti-tank missiles from the US.

The call was included in a whistleblower's complaint that Trump abused his official powers "to solicit interference" from Ukraine in the upcoming 2020 election, and that the White House took steps to cover it up.

Trump has denied any wrongdoing and has insisted the call with Zelensky was "perfect."

Other US officials, however, got the sense that there was a quid pro quo linking US military aid to the Ukrainian investigations, according to their sworn testimony before the House committees.

This included Bill Taylor, the top US diplomat in Ukraine, who had testified that it was his "clear understanding" that US security aid to Ukraine wouldn't be released unless Zelensky announced he would investigate Trump's political rivals.

Republicans say they are planning to build the case in their line of questioning that Taylor didn't have a "clear understanding" of what Trump wanted -- and that his testimony that Trump wanted "everything" withheld until Ukraine announced political investigations is based on a "game of telephone," according to a source involved in the planning.

Similarly, they plan to make that a key focus of their questioning on Wednesday of Deputy Assistant Secretary of State George Kent -- that he didn't have direct knowledge of Trump's motivations.

Republicans say they don't plan to be overly aggressive with Taylor and Kent -- like the way they were with Trump's former lawyer Michael Cohen -- but plan to press these two witnesses in ways to sow doubt about their understanding of what was happening in the White House.

Building on the 18-page staff memo circulated Tuesday morning, Republican sources say they are trying to turn the argument to the substance after weeks of making it about the process. But expect Republicans to complain at Wednesday's hearing about House Intelligence Committee Chairman Adam Schiff's handling of the proceedings.

Trump claimed that the focus of the inquiry is based on second- and third-hand witnesses -- despite many of the witnesses who have testified behind closed doors having first-hand knowledge of potentially improper administration actions regarding US military aid to Ukraine.

The President also reiterated his call Tuesday for former Vice President Joe Biden and his son, Hunter Biden, to testify.

This story has been updated.