(CNN) House Democrats are signaling they are now on a fast-track in their impeachment proceedings, avoiding court battles that could delay their inquiry and limiting the number of witnesses at public hearings -- all signs that President Donald Trump could be impeached as soon as next month.
House Speaker Nancy Pelosi has not shared her thinking on the final timeline with her colleagues, and Democratic sources say the timing is still fluid and could continue to evolve.
But in a series of moves this week, Democrats have shown they are rapidly moving to complete the proceedings by Christmas, something that could result in Trump being just the third president to be impeached in history.
The schedule became apparent in recent days after House Intelligence Chairman Adam Schiff, a California Democrat, announced that public hearings would begin next week and also suggested Thursday there's a limit to the witnesses they would call for the public hearings.
Plus Democrats also withdrew a subpoena of a former White House official to ensure their proceedings were not delayed by a court battle. Schiff also decided Thursday not to subpoena someone who could have been a star witness -- former national security adviser John Bolton, who privately raised concerns about the Ukraine scandal at the heart of the impeachment probe. Schiff's decision came after the former Trump aide's counsel warned they would sue over any subpoena.
"We have no interest in allowing the administration to play rope-a-dope with us in the courts for months," a House Intelligence Committee official said of the decision not to subpoena Bolton.
After weeks of private depositions, the next phases of the House impeachment proceedings could conclude before 2020.
Schiff has announced that three witnesses would testify next week, and Democratic lawmakers expect at least one more week of public hearings before his panel likely to follow on the week of November 18.
The House is then scheduled to take a recess for Thanksgiving week, giving time for Schiff's committee — along with House Oversight and House Foreign Affairs — to finish a report detailing their findings and recommendations of their investigation.
At that point, the House Judiciary Committee would take the lead on the impeachment push — potentially in the first week of December. Democratic sources expect that committee to have a public hearing, possibly in that week, before it votes on articles of impeachment. That vote could occur in committee in the first or second week of December, the sources said.
If that timeline is followed, that would set up a full House vote to impeach Trump on the week of December 16 — a historic vote that could come 21 years after President Bill Clinton was impeached by the House on December 19, 1998.
Still, Democrats are wary about specifying a timeframe.
"I'm not going to speculate on a timeline," House Judiciary Chairman Jerry Nadler said on CNN Thursday. "We want to finish the process as expeditiously as possible and thoroughly ... that the American people see what the evidence is - what the contradictory evidence is if any - and if it's going to be done, it's got to be done right and whatever time required it takes."
House Majority Leader Steny Hoyer told lawmakers this week they should expect to be in session the week of December 16. Hoyer cited the need to pass spending bills to avoid a government shutdown, but it's also possible the time will be used to take up impeachment.
The swift timeline underscores the amount of evidence House investigators have obtained in the two months since a whistleblower complaint was released alleging Trump solicited Ukraine to help his campaign by investigating former Vice President Joe Biden. They've interviewed more than a dozen witnesses behind closed doors, who have said Trump directed his personal attorney Rudy Giuliani to push for Ukraine publicly announcing an investigation as $400 million in US security aid was withheld from Ukraine.
While the House has received cooperation from the witnesses who have testified, many current and former senior Trump officials have declined to testify after receiving subpoenas. Former White House aide Charles Kupperman filed a lawsuit asking a court to decide whether he had to comply with the subpoena, but the House on Wednesday withdrew its subpoena — a sign they are moving on without him.
"Given the schedule of our impeachment hearings, a court process that leads to the dismissal of Dr. Kupperman's flawed lawsuit would only result in delay, so we have withdrawn his subpoena," said an official working on the impeachment inquiry.
Democrats have said they have sufficient evidence already to move forward on impeachment, even if senior officials such as Bolton, Energy Secretary Rick Perry and acting White House chief of staff Mick Mulvaney ultimately do not testify.
Schiff has declined to put a timeline on the impeachment probe, but he has lauded the committee's "rapid progress" on the inquiry and said Wednesday the public hearings would show"the most important facts are largely not contested."
And in a letter Thursday to Republican Rep. Devin Nunes inviting Republicans to propose potential witnesses, Schiff signaled that there is a limit to the number of witnesses they plan to hear from.
"The majority does not intend to request public testimony from every witness who previously testified in depositions or interviews as part of the impeachment inquiry," Schiff wrote.
CORRECTION: This story has been updated to reflect that the House is setting up a floor vote 21 years after President Bill Clinton was impeached.