WASHINGTON (AP) — It's impeachment because House Speaker Nancy Pelosi says it is.?

That's the legal position of House Democrats, and they are sticking with it, for now, even as President Donald Trump decries impeachment as "illegitimate" without a formal House vote to start it. Trump has said he won't cooperate with the impeachment investigation, which is looking into his dealings with Ukraine, unless there is a vote and Republicans are treated more fairly.

For the Democrats, there are legal, strategic and political reasons to stay the course.

THE LEGAL RATIONALE

Under the law, Democrats say they have no obligation to hold a vote. The Constitution gives the House "the sole power of impeachment" and the Senate "the sole power to try all impeachments." And it dictates the removal from office of an impeached president who is convicted by the Senate of "treason, bribery, or other high crimes and misdemeanors."

Congress is left to fill in the details. And there is no requirement for a vote under House rules.

Republicans are pointing to precedent. They note that the House held votes to authorize impeachment investigations against Presidents Richard Nixon and Bill Clinton.

In an Oct. 3 letter to Pelosi questioning whether she would hold a vote to start the process, House Minority Leader Kevin McCarthy, R-Calif., said the speaker had so far given no indication whether "key historical precedents or basic standards of due process will be observed."

Pelosi responded that House rules allow committees to conduct investigations, including impeachment investigations.

"There is no requirement under the Constitution, under House rules, or House precedent that the whole House vote before proceeding with an impeachment inquiry," Pelosi wrote.

___

Without a vote, Democrats are able to craft the investigation however they see fit — and leverage a vote if it becomes necessary later on.

In his letter, McCarthy asked Pelosi if she planned to allow Republicans as part of impeachment to have equal subpoena power or give the president's lawyers a chance to cross-examine witnesses.

A resolution to authorize an impeachment inquiry could potentially set some of those rules. But without a vote, Pelosi doesn't have to answer any of those questions or give Republicans any of those privileges.

A vote would also take time, and Democrats have said they want to complete the investigation quickly as the election year approaches. They also note that public support for impeachment has increased.

If a vote to formalize impeachment becomes necessary for any reason, Pelosi could always hold one later. In the impeachment inquiry of President Nixon — which was never completed because he resigned — the House didn't officially vote to start the impeachment probe until months after the investigation had started.

___

THE POLITICS

Pelosi is also likely weighing the politics. If she were to hold a vote in response to Trump's letter, she could be seen as backing down.

And it could put some of her members in a tough position. While almost all the Democrats, including most of the moderate freshman Democrats who helped flip Republican districts in 2018, now support the inquiry, few are pushing to have a vote on the House floor. A vote launching impeachment could be used against them in campaign ads, and Trump and the GOP have made clear they intend to campaign on the issue in 2020.

For now, Pelosi is holding her cards close.

"If we want to do it, we'll do it. If we don't, we don't," Pelosi said in an interview with the Atlanta Journal Constitution last week. "But we're certainly not going to do it because of the president."

Follow President Donald Trump as he shapes America’s future!