Evan Vucci/AP Photo

President Donald Trump on Thursday argued that stock markets would crash if Democrats impeached him.

"If they actually did this the markets would crash," the president tweeted. "Do you think it was luck that got us to the best Stock Market and Economy in our history. It wasn't!"

House Speaker Nancy Pelosi launched a formal impeachment inquiry into the president on Tuesday amid news Trump had pressured Ukraine's leader to investigate the 2020 Democratic presidential candidate Joe Biden and his son Hunter.

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President Donald Trump on Thursday argued that stock markets would crater if Democrats impeached him.

"If they actually did this the markets would crash," Trump tweeted. "Do you think it was luck that got us to the best Stock Market and Economy in our history. It wasn't!"

Twitter/Donald Trump

Trump was responding to a tweet by the Fox Business host Maria Bartiromo that said "Stocks hit session lows after Pelosi calls for impeachment inquiry." Fears of political turmoil rattled global markets Wednesday.

The S&P 500 has posted meager gains over the last 12 months, reflecting fears over Trump's trade war with China and the impact of his tariffs on the growth of the global economy.

House Speaker Nancy Pelosi launched a formal impeachment inquiry into the president on Tuesday after news emerged that Trump had pressured Ukraine's president to investigate the 2020 Democratic presidential candidate Joe Biden and Biden's son Hunter. After initially resisting, the White House has released a memo of the call and turned over a whistleblower complaint involving the conversation.

"The actions taken to date by the president have seriously violated the Constitution," Pelosi said in her speech announcing the official inquiry. "The president must be held accountable. No one is above the law."

"You will see it was a very friendly and totally appropriate call," Trump tweeted on Tuesday. "No pressure and, unlike Joe Biden and his son, NO quid pro quo!"

A few hours later, he tweeted the impeachment inquiry amounted to "PRESIDENTIAL HARASSMENT."

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