Impeachment 'drug deal' witness Bolton agrees to testify at Trump trial, defying WH

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John Bolton, Trump’s former National Security Adviser, is now “prepared to testify” at Trump’s impeachment trial, after many efforts to stonewall. MSNBC Chief Legal Correspondent Ari Melber reports on how Bolton’s testimony has “single-handedly reignited the witness debate” by joining the “ranks of people” who argue a “serious trial should include fact witness.”