WASHINGTON (AP) — The White House letter vowing to defy what it calls the "illegitimate" impeachment inquiry has put President Donald Trump on a more certain path to actual charges. His refusal to honor subpoenas or allow testimony would likely play into formal accusations against him.

The letter sent by White House Counsel Pat Cipollone said the president would not participate in the impeachment investigation. Democrats say that just gives them reason to write an article of impeachment charging obstruction.

The White House insists that a formal House vote is necessary to start impeachment, but Democrats are moving ahead without one. They say the Constitution gives them the sole power to decide how impeachment is conducted.

Speaker Nancy Pelosi said Trump "will be held accountable" as polls indicate increased public support for impeachment.

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