Trump has enlisted parts of the US government and key allies in the pursuit of unproven or disproven conspiracy theories.
Previously, House Democrats have subpoenaed acting OMB Director Russel Vought and Secretary of State Mike Pompeo.
It's not just openly critical Republicans like Sen. Mitt Romney who have drawn Trump's ire — he is also angry at those who haven't defended him.
Insider's most recent poll found that only 30% of Americans are against impeaching Trump, while a plurality support it.
President Trump publicly called on Ukraine and China to investigate the former Vice President Joe Biden and his son last week.
House Intelligence Committee Chairman Adam Schiffer said an agreement has been reached for the Trump-Ukraine whistleblower to testify before Congress.
A whistleblower complaint that an intelligence official filed against Trump cites multiple White House officials as being the source of the complaint.