The judiciary committee of the House of Representatives, which is dominated by Democrats, sent letters demanding documents to more than 80 family members, political contacts, business contacts and institutions connected to the president.
Republican Adam Schiff, who chairs the House intelligence committee, also stressed that it's too early to make judgments about impeachment.
"I think Congressman Nadler made a decision to impeach the President the day the President won the election", House Minority Leader Kevin McCarthy said on "This Week".
Investigators for the House Judiciary Committee are now looking into the matter.
"You know, there are a lot of people in this country that say, listen, if Mueller didn't find anything, why the hell are we going to have more and more investigations?" While Republicans bend over backward to defend the president in order to please their base voters - the people they need to mollify if they're to withstand primary challenges - they will alienate the rest of the voting public.
"We're waiting for a report by people who weren't elected", he told a crowd of cheering conservatives.More news: Henderson: Derby draw disappointing, but we'll stay positive
"Now we have people that lost and unfortunately when you put the wrong people in a couple of positions, and they leave people for a long time that shouldn't be there, and all of a sudden they're trying to take you out with bull***", Trump said.
U.S. President Donald Trump speaks at the Conservative Political Action Conference (CPAC) annual meeting at National Harbor in Oxon Hill, Maryland, U.S., March 2, 2019. Investigators have examined key episodes such as Mr. Trump's firing of FBI Director James Comey and Mr. Trump's fury over Attorney General Jeff Sessions' recusal. "You have to persuade enough of the opposition party voters, the Trump voters", Nadler said.
Trump fueled suspicions previous year about his ties with Russian Federation when, in a sharp break with standard diplomatic practice, he dismissed top aides for two hours of talks with Putin during their first formal summit, in Helsinki.
The speech - clocking in at more than two hours - also included sharp attacks on former Attorney General Jeff Sessions, former Federal Bureau of Investigation head James Comey, the Democratic Party and those critical of his approach to North Korea.
House Democrats are undertaking several broad investigations that reach far beyond Mueller's focus on Russian interference in the 2016 election and possible collusion between Russians and the Trump campaign.
Yet delivering a reaction that is too muted or measured might lose votes during the party's nominating battle, where the Russian Federation investigation and attacking Trump animate the base. Please, Russia, please! Please get us the emails! That is another unresolved question that Mueller is pursuing.
Trump also touched on various other topics, from Robert Mueller's investigation to America's recent economic successes, the border wall situation, and trade negotiations with China.