WASHINGTON — Ahead of the first public testimony of the impeachment inquiry next week, the White House and key Hill Republicans are discussing a defense of President Donald Trump that is heavy on offense, with a focus on dismissing and discrediting witnesses whose testimony may be damaging to the president.

“If folks question the motivations and credibility of the president as we go through this, it’s possible that the same standard could apply to them,” said an administration official involved in the process granted anonymity to speak candidly about strategy, who said the approach had been used during past impeachment defenses.

The president's congressional backers are likely to question the standing of witnesses expected to provide the toughest assessments of his conduct in requesting the government of Ukraine investigate Hunter Biden, son of 2020 rival Joe Biden, the former vice president.

Some key Hill GOP allies of the president are looking to the combative Brett Kavanaugh confirmation hearings as a model for what they view as a successful effort to chip away at the credibility of a potentially damaging witness, according to a person familiar with the White House’s thinking.

The strategy for limiting the damage to the president from the upcoming hearings, developed by White House aides in concert with Republican allies in Congress, also includes an effort to emphasize distance between the witnesses — who include three career diplomats — and the president, according to people familiar with the discussions.

The questioners are expected to emphasize that none of the witnesses providing public testimony had a direct conversation with Trump about a link between Ukraine funding and an investigation into the Bidens, said an administration official. Instead, the White House is hoping the hearings will suggest witness allegations of an explicit quid pro quo predicating security assistance for Ukraine on the public announcement of an investigation of the Bidens were based on conversations among themselves.

The White House has asserted executive privilege to block witnesses from discussing their conversations with the president, preventing anyone who would have had a direct conversation with Trump from testifying. A majority of the current and former White House officials who may have direct knowledge of the conversation and whose testimony was requested or subpoenaed by House lawmakers this week have declined to appear.

While Democrats are anticipating the testimony starting Wednesday will boost their public case for impeachment, White House officials say they are optimistic the event, like other high-profile hearings they have weathered, won't be as damaging as anticipated.

The first open hearings as part of the House impeachment inquiry, to be held Nov. 13, are scheduled to feature testimony from career diplomat William Taylor and State Department official George Kent. The second hearing, scheduled for Nov. 15, is expected to include testimony from former U.S. ambassador to Ukraine Marie Yovanovitch.

In transcripts of closed door testimony released this week, the three painted a picture of a shadow foreign policy run by Trump’s personal lawyer Rudy Giuliani ,who was mounting a pressure campaign on Ukraine to investigate business dealings in Ukraine by Joe Biden's son, and conspiracy theories on that nation's possible role in 2016 election interference.

Taylor said he was told Trump had ordered a hold on military assistance to Ukraine and that it was his “clear understanding” the money wouldn’t be released until the Ukrainian president publicly committed to investigate the Bidens. Kent testified that he witnessed an effort to push politically motivated investigations “injurious to the rule of law,” according to the transcript.

Trump floated the argument that none of the witnesses had firsthand knowledge of his thinking on Ukraine on Friday as he took questions from reporters before departing the White House.

“For the most part, I've never even heard of these people, I have no idea who they are,” Trump said. “...It seems that nobody has any firsthand knowledge, there is no firsthand knowledge.”

He said of European Union ambassador and Trump donor Gordon Sondland, “I hardly know the gentleman.” Sondland first testified that Trump told him there was no quid pro quo, though later amended his testimony to say that he had “presumed” there was one and told the Ukrainians they likely wouldn’t get funding until they made a statement about the investigations.

Meanwhile, Trump has been working to ensure his support from Senate Republicans remains solid. In a reminder to Republicans of why they should support him, he held an event Wednesday touting the number of conservative judges he has appointed where he heaped praise on key Senate Republicans such as Iowa’s Chuck Grassley and South Carolina’s Lindsey Graham — senators whose support he will need if he faces an impeachment vote in the Senate.

White House advisers say they feel confident Trump can weather the public phase of the impeachment process, since Republican voter support for the president remains strong — an indication, said a White House official, that GOP senators up for re-election in 2020 will need to stick by Trump, or risk facing a primary challenger.