WASHINGTON  — President Donald Trump said Friday the White House is preparing a letter to House Speaker Nancy Pelosi formally objecting to the Democrats conducting their impeachment inquiry without an official vote. The letter is expected to say the administration won't cooperate with the probe without that vote — but he also said he believes it will pass.

Trump acknowledged that Democrats in the House "have the votes" to begin a formal impeachment inquiry, but said he is confident they don't have the votes to convict in the GOP-controlled Senate. And he also said he believes the move will backfire on Democrats politically.

"I really believe that they're going to pay a tremendous price at the polls," he said.

Pelosi last week announced that the House was beginning the inquiry but didn't seek the consent of the full chamber, as was done for impeachment investigations into former Presidents Richard Nixon and Bill Clinton.

Two days after telling reporters, "Well, I always cooperate," Trump struck a different note on cooperating with the House probe. "I don't know," he said. "That's up to the lawyers."

Trump allies have suggested that without a formal vote, the House is merely conducting standard oversight, entitling lawmakers to a lesser level of disclosure from the administration. The Justice Department raised similar arguments last month, though that was before Pelosi announced the impeachment investigation.

In a letter Thursday to House Minority Leader Kevin McCarthy, Pelosi argued, "There is no requirement under the Constitution, under House Rules, or House precedent that the whole House vote before proceeding with an impeachment inquiry."

There's no clear-cut procedure in the Constitution for launching an impeachment inquiry, leaving many questions about possible presidential obstruction untested in court, said Allan Lichtman, a history professor at American University.

"There's no specification in the Constitution in what does and does not constitute a more formal impeachment inquiry or investigation," he said.

Rudy Giuliani, the president's personal attorney, dismissed the entire premise of the impeachment inquiry, which is centered on Trump asking Ukraine to investigate his possible political rival, Democratic former Vice President Joe Biden.

"The president was not tasking Ukraine to investigate a political opponent," Giuliani told The Associated Press on Thursday. "He wanted an investigation into a seriously conflicted former vice president of the United States who damaged the reputation of the United States in Ukraine."

Democrats have sought to use their declared impeachment investigation to bolster their case to access all sorts of documents from the administration, most recently secret grand jury information that underpinned special counsel Robert Mueller's report on Russian interference in the 2016 election. They have also threatened to use the administration's refusal to turn over documents and make witnesses available to potentially form an article of impeachment over obstruction of the congressional inquiry.

Where courts have generally required congressional oversight requests to demonstrate a legitimate legislative purpose, impeachment requests could be wide-ranging.

It is unclear if Democrats would wade into a lengthy legal fight with the administration over documents and testimony — or if they would just move straight to considering articles of impeachment.

Pelosi has sought to avoid a vote on the impeachment probe for the same reason she resisted, for months, liberal calls to try to remove the president: It would force moderate House Democrats to make a politically risky vote.

The White House, meanwhile, is trying to force the question on Democrats, as it seeks to raise the political cost for their impeachment investigation and to animate the president's supporters ahead of the 2020 election.

------

Lemire reported from New York.