President Trump on Thursday publicly urged China to investigate Democratic challenger Joe Biden, a new request that a foreign government assist his reelection campaign adding to the extraordinary pattern of conduct at the center of a fast-accelerating impeachment inquiry.

With his brazen and direct appeal to the Chinese, delivered before journalists assembled on the South Lawn of the White House, Trump seemed to make a mockery of the charge that he abused the power of his office by pressing his Ukrainian counterpart to examine unfounded allegations of corruption by Biden and his son Hunter.

Trump’s plea to China for an investigation into the Bidens came almost immediately after he addressed his acrimonious trade war with China. “I have a lot of options on China,” Trump warned, “but if they don’t do what we want, we have tremendous power.”

When a reporter then asked what he had hoped Ukrainian President Volodymyr Zelensky would do following their July 25 phone call, Trump replied: “If they were honest about it, they’d start a major investigation into the Bidens. It’s a very simple answer. They should investigate the Bidens.”

Trump’s remarks underscored his claim that he did nothing improper by calling on a foreign power to investigate a domestic political opponent, a move his critics consider an egregious violation of his constitutional oath.

Trump’s statement about China effectively globalizes the argument he has been making domestically, calling on other countries to stand with the United States under his rule or against it. It could signal to other countries that one way to curry favor with the United States is by digging up damaging information about Democrats.

Thursday also marked the latest instance of Trump saying aloud something that almost certainly would be a major scandal if revealed from a private conversation. Trump’s request of China echoed his “Russia, if you’re listening . . .” appeal during the 2016 campaign for the Russian government to steal Hillary Clinton’s missing emails and release them.

“Someone should inform the president that impeachable offenses committed on national television still count,” Clinton tweeted Thursday.

Trump and his allies have provided no evidence to back up their claims of wrongdoing. Hunter Biden joined the board of an investment advisory firm whose partners included Chinese entities shortly after visiting China in 2013 with his father while he was vice president. George Mesires, an attorney representing Hunter Biden, has said that his client acquired a 10 percent equity stake in the firm in October 2017, and as of this summer that stake was worth about $430,000.

On Capitol Hill, meanwhile, Democratic leaders denounced Trump’s China comments and appeared dumbfounded that the president had given them live ammunition to use against him in their impeachment proceedings.

“The president of the United States encouraging a foreign nation to interfere again to help his campaign by investigating a rival is a fundamental breach of the president’s oath of office,” House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) told reporters. “It endangers our elections, it endangers our national security, it ought to be condemned by every member of this body, Democrats and Republicans alike.”

Washington Post White House Bureau Chief Philip Rucker analyzes the mood in the White House as support for an impeachment inquiry grows. (The Washington Post)

House investigators deposed the first major witness in the Ukraine matter, Kurt Volker, who resigned last week as U.S. special envoy for Ukraine after being named in the whistleblower complaint that sparked the impeachment inquiry. Following the nearly 10-hour deposition, House investigators released text messages provided by Volker illustrating how at Trump’s behest, senior State Department officials coordinated with a Ukrainian official and Trump’s lawyer Rudolph W. Giuliani to leverage a summit between the two heads of state on the Ukrainian president’s promise to investigate the 2016 election and an energy company that employed Hunter Biden.

Also Thursday came the revelation that Trump ordered the swift removal of the U.S. ambassador to Ukraine, Marie Yovanovitch, this year after hearing concerns from Giuliani, as well as former Texas congressman Pete Sessions, among others, outside of the administration, a senior administration official confirmed. Trump’s role in the ambassador’s ouster was first reported by the Wall Street Journal.

Giuliani complained in a recent interview with The Washington Post that Yovanovitch obstructed efforts to persuade the Ukrainians to investigate the Bidens. “She is running around the streets of Ukraine going against the elected president of the United States,” Giuliani said.

Congressional Republicans, who rarely speak a cross word about the president, barely blinked at his China remark. The muted response from GOP lawmakers about Trump’s call for China to investigate Biden presented a stark contrast to earlier this week, when many spoke out after the president tweeted congratulations to Chinese President Xi Jinping in celebration of the 70th anniversary of communist rule in Beijing.

By Thursday, however, most of those voices fell silent on Trump’s latest Chinese assertion. Minutes after Trump called on China to investigate Biden, House Minority Leader Kevin McCarthy (R-Calif.) tweeted a link to a letter he sent House Speaker Nancy Pelosi (D-Calif.) that morning asking her to suspend the impeachment inquiry until she answers questions about the process.

Rather than condemning Trump’s appeal to the Chinese, McCarthy prodded the speaker for clarity on whether the House would vote on an official impeachment inquiry, or whether Republicans would get subpoena power to call their own witnesses.

“As you know, there have been only three prior instances in our nation’s history when the full House has moved to formally investigate whether sufficient grounds exist for the impeachment of a sitting President,” McCarthy wrote. “I should hope that if such an extraordinary step were to be contemplated a fourth time it would be conducted with an eye toward fairness, objectivity and impartiality.”

Pelosi responded to McCarthy’s missive by noting that his request came “shortly after the world witnessed President Trump on national television asking yet another foreign power to interfere in the upcoming 2020 elections.”

“As you know, our Founders were specifically intent on ensuring that foreign entities did not undermine the integrity of our elections,” Pelosi wrote.

Rep. Daniel Kildee (D-Mich.), a deputy whip on Pelosi’s leadership team, said Trump’s comment “certainly strengthens our case that this president is abusing his power in a way that is really dangerous for America.” He speculated that Trump intentionally was “trying to say openly and publicly the things he knows he’s going to get caught having said privately to normalize and soften the reaction.”

Kildee recalled that during the special counsel’s Russia investigation Trump insisted that “he would never enlist foreign interference … ‘No collusion! No collusion!’ Then he gets caught colluding with Ukraine. I think he’s now decided that the only way he can survive this is to do what he has been doing in secret in a very public way in order to normalize it.”

Sen. Lindsey O. Graham (R-S.C.), usually one of the president’s loyal defenders, said in an interview Thursday that he did not agree with the call for China to investigate the Biden family.

“I don’t want to go down that road,” Graham said. He tried to explain Trump’s request by adding, “It’s the president pushing back. He feels like everyone is coming after him all the time and he hasn’t done anything wrong.”

Vice President Pence, traveling in Arizona, was a voice of support. Asked about Trump’s call for China to investigate the Bidens, the vice president told reporters, “I think the American people have a right to know if the vice president of the United States or his family profited from his position as vice president in the last administration.”

Pence had a different position in 2016 when he was running for vice president. During his debate with Sen. Tim Kaine (D-Va.), Pence said, “This is basic stuff. Foreign donors, and certainly foreign governments, cannot participate in the American political process.”

Trump, meanwhile, continued his defiant stance Thursday, lashing out at Democrats and the media as he deviated from prepared remarks promoting Medicare, making an official White House event feel like a campaign rally. Addressing residents of The Villages, a retirement community in Florida, Trump mused about staying in office beyond his legal limit of two terms.

“If you want to drive them crazy, just say eight more years or 12 more years or 16 . . . you’d really drive them into the loony bin,” Trump said. “That’s why they do the impeachment crap, because they know they can’t beat us fairly.”

Trump mocked Biden’s standing in the Democratic nominating contest and said Sen. Elizabeth Warren (D-Mass.) was his likeliest opponent because “she came up from the ashes.” He called the Democrats “maniacs” and suggested that if they take back the White House “the country’s going to go to hell.”

Trump also went on an extended rant about CNN’s coverage of him and then proposed creating a government-run television news network to compete with the independent media.

“We ought to start our own network and put some real news out there because they are so bad,” Trump said. He added, “We are looking at that. We should do something about it, to put some really talented people and get a real voice out there, not a voice that’s fake.”

Trump also bizarrely accused pharmaceutical companies of being behind the House Democrats’ push for impeachment because of his administration’s work to lower drug prices.

“I wouldn’t be surprised if the hoax didn’t come a little bit from some of the people that we’re taking on,” Trump said, later singling out the pharmaceutical industry. The president provided no evidence for his claim.

Asked to respond, Holly Campbell, a spokeswoman for the industry group PhRMA, said, “Not to be so frank, but it is ridiculous you are asking me about it. Of course we are not.”

Josh Dawsey, Paul Kane, Toluse Olorunnipa and John Wagner contributed to this report.