WASHINGTON (AP) - House Speaker Nancy Pelosi plans to announce a formal impeachment inquiry of President Donald Trump over allegations that he pressured the leader of Ukraine to investigate Joe Biden's family.

Pelosi's likely decision was described to The Associated Press by a person familiar with the decision who was not authorized to speak publicly and spoke on condition of anonymity.

Pelosi had for months resisted calls to start the impeachment process. But the dynamic changed this week as more members of her caucus came out in support, including Democrats from swing districts.

Democrats are demanding information about whether Trump improperly pressured the Ukrainian president to investigate Biden and his son, partly by withholding foreign aid.

Trump insists he did nothing wrong and said he will release an unredacted transcript of a call with Ukraine's leader on Wednesday.

Trump is asserting that a formal impeachment inquiry by House Democrats would be a "positive for me."

The president is in New York meeting with world leaders at the United Nations. He says the country is "doing the best it's ever done" and that Democrats are going to lose next year's elections if they pursue impeachment. He says: "If she does that, they say that's a positive for me."

A formal announcement is expected at a 4 p.m. news conference.

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