Republicans have circulated a lengthy memorandum to their members on the House Intelligence, Oversight and Foreign Affairs committees that lays out their strategy ahead of public impeachment hearings this week, with plans to make the case that it's important to understand President Donald Trump's "state of mind" during his July 25 phone call with Ukrainian President Volodymyr Zelenskiy that's at the center of their impeachment probe.

“To appropriately understand the events in question — and most importantly, assess the President’s state of mind during his interaction with [Ukrainian] President Zelensky — context is necessary,” the 18-page memo obtained by ABC News reads.

"This context shows that President Trump has a deep-seated, genuine, and reasonable skepticism of Ukraine and U.S. taxpayer-funded foreign aid, independent of and proceeding any mention of potential investigations of Ukraine's interference in the 2016 elections or Hunter Biden's involvement with Burisma, a notoriously corrupt company."

Republicans plan to focus on what they say are four key pieces of evidence during the hearings.

1) "The July 25 call summary -- the best evidence of the conversation -- shows no conditionality or evidence of pressure," 2) "President Zelensky and President Trump have both said there was no pressure on the call," 3) The Ukrainian government was not aware of a hold on U.S. security assistance at the time of the July 25 call," and 4) "President Trump met with President Zelensky and U.S. security assistance flowed to Ukraine in September 2019--both of which occurred without Ukraine investigating President Trump's political rivals." Trump also allegedly wanted the aid withheld unless there was an investigation into a largely debunked theory that it was Ukrainians, not Russians, who tried to interfere in the 2016 election – on behalf of Hillary Clinton – and the Democrats' purported efforts on that front.

Zelenskiy has asserted that there was "no blackmail" in the July call that led the House to open a formal impeachment inquiry into the president.

"There was no blackmail. It was not the subject of our conversation," he said. "The call could have no impact on our relations with America."

At the heart of the inquiry is Trump’s July 25 phone call with Zelenskiy and whether the administration withheld nearly $400 million in aid and a White House summit between the two leaders in exchange for an investigation into the president’s political rival, former Vice President Joe Biden and his son, Hunter for his work on the board of Ukrainian energy company Burisma.

A White House official listening to Trump’s July 25 phone call with Ukraine’s president described the call as “crazy” and “frightening” and was “visibly shaken,” according to notes taken by the intelligence official who filed a formal whistleblower complaint after speaking with the official, and others.

According to a rough transcript of the call released by the White House, Trump asked Ukraine’s president to launch an investigation into Biden and his son.

Republicans have criticized the way in which the majority has handled the proceedings — so far, they’ve taken place behind closed doors until this week. Still, Republicans have also been critical of the formal impeachment procedures, which included the move to public hearings and which were passed by a vote on the House floor last month.

On Saturday, House Intelligence Committee Republicans submitted their request for witnesses. It includes a call for the unnamed “whistleblower” but does not identify the individual. In response, House Intelligence Chairman Adam Schiff wrote that testimony from the alleged whistleblower would be "redundant and unnecessary" and adds that in light of the president's threats, that individuals appearance "would only place their personal safety at grave risk."