Senate Minority Leader Chuck Schumer says President Trump should testify before the U.S. Congressional impeachment hearings instead of expressing his concerns on Twitter. At a press conference in New York, Senator Schumer echoed House Speaker Nancy Pelosi's call on Sunday for President Trump to directly make his case to the House impeachment inquiry. Trump has regularly tweeted arguments in his own defense, and he has lashed out on Twitter at both Democrats and witnesses in the public impeachment hearings.On Sunday, Trump blasted another witness in Congress' impeachment inquiry against him, saying Jennifer Williams, a foreign policy aide to Vice President Mike Pence was a "Never Trumper" who should "work out a better presidential attack."Trump two days ago attacked another witness, former U.S. Ambassador to Ukraine Marie Yovanovitch, while she was testifying in a public hearing of the impeachment inquiry."Everywhere Marie Yovanovitch went turned bad," Trump said on Friday, a moment that Democrats said amounted to witness intimidation.Trump's July 25 phone call is at the heart of the House of Representatives' Democratic-led inquiry into whether the Republican president misused U.S. foreign policy to undermine former Democratic Vice President Joe Biden, one of his potential opponents in the 2020 election.Trump says his call with Ukrainian President Volodymyr Zelenskiy was "perfect."The White House has released a rough transcript of the July 25 call, as well as another call in April in which Trump congratulated Zelenskiy on his election.