WASHINGTON - President Donald Trump said Monday that he will "strongly consider" testifying in writing as part of the impeachment inquiry at the outset of a week in which eight current and former officials are scheduled to publicly testify about his controversial actions regarding Ukraine.

In morning tweets, Trump said he might take up House Speaker Nancy Pelosi, D-Calif., on a suggestion she made over the weekend. Trump also claimed that the rules of the inquiry had been "rigged" by Pelosi and House Intelligence Committee Chairman Adam Schiff, D-Calif.

"Even though I did nothing wrong, and don't like giving credibility to this No Due Process Hoax, I like the idea & will, in order to get Congress focused again, strongly consider it!" Trump said in tweets in which he also disparaged Pelosi.

Democrats conducting the impeachment inquiry are seeking to prove that Trump leveraged military assistance and an Oval Office meeting in exchange for investigations of former Vice President Joe Biden and his son Hunter Biden, and a debunked theory concerning purported Ukrainian interference in the 2016 presidential election.

Pelosi said in a letter to Democratic colleagues on Monday that the facts of the impeachment inquiry are "uncontested," asserting that Trump "abused his power for his own personal, political benefit, at the expense of our national security interests."

She also pushed back against those who have suggested "no serious wrongdoing" was committed because military aid that was withheld to Ukraine was eventually released without the launch of investigations sought by Trump.

"None of us comes to Congress to impeach a President, but rather to make progress for America's working families," she said. "However, our first order of business is our oath to support and defend the Constitution from all enemies foreign and domestic."

Congressional Democrats reacted to Trump's statement about testifying with skepticism and calls for more cooperation from the White House.

Rep. Don Beyer, D-Va., said in a tweet that the president should testify and allow the testimony of other officials, claiming Trump was engaged in an "illegal coverup."

"He should allow Rick Perry and John Bolton and Rudy Giuliani to testify," Beyer tweeted, referring to the energy secretary, former national security adviser and the president's personal lawyer. "He should turn over the documents Congress subpoenaed. He should end his illegal coverup. I'm not holding my breath."

Rep. Lee Zeldin, R-N.Y., a staunch Trump ally, also said that it would be beneath the president to provide testimony in the impeachment inquiry.

"It would be a 'heck no' from me as far as whether or not he should testify," Zeldin said during an interview on Fox News.

Republicans also reiterated their complaint that public hearings are being held before all deposition transcripts have been released, claiming that Democrats are withholding information from the public.

Democrats are giving witnesses a chance to review transcripts of their closed-door testimony before releasing them publicly.

Rep. Mark Meadows, R-N.C., also suggested Democrats don't want Americans to view all of the information.

"Not being discussed enough: House Democrats are holding public impeachment hearings when critical depositions haven't been released - some that include key exculpatory information for the President," he wrote. "Perhaps it's because they're not interested in you seeing the full set of facts."

Senate Minority Leader Mitch McConnell, R-Ky., said he "can't imagine a scenario" in which his chamber would vote to remove Trump if he is impeached by the House. Removal by the Senate requires a two-thirds vote of the chamber.

Seventy percent of Americans think Trump did something wrong regarding Ukraine, according to a new ABC-Ipsos poll.

In the poll, 51 percent agreed that Trump had done something wrong and said he should be impeached by the House and removed from office by the Senate. Another 6 percent agreed that Trump had done something wrong and said he should be impeached but not removed from office. Another 13 percent agreed that he had done something wrong but said he should not be impeached or removed.

Secretary of State Mike Pompeo said he "always" defends State Department employees, although he declined to defend individual officials who have testified in the impeachment inquiry, including former ambassador to Ukraine Marie Yovanovitch and her successor, acting ambassador William Taylor

Yovanovitch told the House Intelligence Committee on Friday that Trump recalled her this year after a "smear campaign" aimed at advancing corrupt interests in Ukraine. As she was testifying, Trump disparaged Yovanovitch in a tweet, prompting an outcry from some Democrats who described the president's actions as witness intimidation.

At a news conference Monday on U.S. policy toward Israel, Pompeo was asked why he hasn't spoken out in defense of his employees.

"I'm happy to talk about Ukraine policy today," Pompeo replied. "I'm not going to get into the issues surrounding the Democrat impeachment inquiry. Just not going to do it today."

Eight witnesses are scheduled to testify publicly this week in the impeachment inquiry, including four on Tuesday.

Lt. Col. Alexander Vindman, European affairs director at the National Security Council, and Jennifer Williams, Vice President Mike Pence's special adviser on Europe and Russia, are scheduled to appear on Tuesday morning.

Vindman testified in a closed-door deposition last month that he "did not think it was proper" for Trump to seek a Ukrainian investigation of a U.S. citizen. He was among those who listened in on the July 25 call between Trump and Ukrainian President Volodymyr Zelensky. Vindman later reported his concerns.

The closed-door testimony of Williams, which was released Saturday, suggests that the Office of Management and Budget had clamped down on Ukraine military aid more than two weeks earlier than has been previously reported.

Trump attacked Williams in a tweet on Sunday.

"Tell Jennifer Williams, whoever that is, to read BOTH transcripts of the presidential calls, & see the just released statement from Ukraine," Trump said. "Then she should meet with the other Never Trumpers, who I don't know & mostly never even heard of, & work out a better presidential attack!"

Tim Morrison, the top Russia and Europe adviser on the National Security Council, and Kurt Volker, a former Trump administration envoy to Ukraine, are scheduled to testify Tuesday afternoon.

Morrison told House investigators last month that Gordon Sondland, ambassador to the European Union, was acting at Trump's behest and spoke to a top Ukrainian official about exchanging military aid for political investigations.

Trump has said he does not know Sondland well and has tried to distance himself from the E.U. ambassador, whom Trump put in charge of Ukraine policy along with two others, even though Ukraine is not part of the European Union.

Volker told impeachment investigators he worked with Trump personal lawyer Giuliani, the White House and Ukrainian officials to arrange the July 25 phone call between Trump and Zelensky, as well as a potential White House visit, while pushing for investigations into Trump's political enemies.

Sondland is scheduled to testify on Wednesday morning. Laura Cooper, the Pentagon official who oversees Ukraine policy, and David Hale, undersecretary of state for political affairs, are scheduled in the afternoon.

On Thursday, Fiona Hill, the former National Security Council Russia adviser, is scheduled to appear.

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The Washington Post's Seung Min Kim contributed to this report.