WASHINGTON – House Speaker Nancy Pelosi says she wants to move "expeditiously" on the impeachment inquiry into whether President Donald Trump abused his power by pushing Ukraine to investigate his political rival, Joe Biden.

At the center of the inquiry, which was launched last week, is a complaint from an unidentified intelligence agency official. The complaint accuses Trump of having "used the power of his office" to solicit foreign interference to discredit Biden, the 2020 Democratic frontrunner. It also alleges that White House officials sought to "lock down" records of a July 25 phone call between Trump and Ukraine President Volodymyr Zelensky in which the president urged Zelensky to investigate Biden and his son, Hunter, who once had business interests in Ukraine.

Trump contends he did nothing improper and accuses Democrats of wanting to overturn the results of the 2016 election.

Some lawmakers want the House to decide whether to file articles of impeachment by Thanksgiving, a timeline that could avoid having the issue spill over into the 2020 election year.

Here's what we know about the process, what's happening next and the key players:

What is an impeachment inquiry?

Basically, an impeachment inquiry is the fact-finding stage of the impeachment process and largely what House Democrats have been doing for months on various other matters involving Trump.

Since taking over the House after the 2018 midterms, six House committees have been investigating a series of allegations against the president, including whether Trump obstructed justice in special counsel Robert Mueller’s probe of Russian interference in the 2016 election, whether he profited unconstitutionally from his namesake business while in office and whether he violated campaign laws by paying hush money to a porn actress before the election.

And Pelosi has said the Ukraine matter would be the primary target of any possible impeachment charges.

The plan for now, according to lawmakers, is to prioritize the Ukraine investigation, which is being led by the House Intelligence Committee, while other panels wrap up their probes and send their best cases to the House Judiciary Committee.

Then lawmakers will decide whether to bring forward articles of impeachment, which would require a full House vote. If it passes, Trump would be impeached – sort of like a criminal indictment.

The process then would shift to the Senate, where an impeachment trial would take place. Basically, House lawmakers would act as prosecutors and senators as the jury for a trial deciding whether to remove Trump from office. After the trial, senators would take a vote. A two-thirds majority is needed for Trump to be removed from office.

While the Constitution puts the responsibility of holding an impeachment trial in the hands of the Senate, there has been some speculation that Senate Majority Leader Mitch McConnell might refuse to hold a trial.

McConnell was asked last March by NPR – before the Ukraine allegation surfaced – about what he saw as the Senate's responsibility. McConnell said at the time that he thought the Senate would have "no choice" on the matter, saying if articles pass the House it would move to the Senate and it "immediately goes into a trial."

What's happening next?

Despite Congress going on a two-week recess, things are moving rapidly. A series of depositions are scheduled with some of the figures wrapped up in the Ukraine scandal, one hearing is scheduled and a host of new subpoenas could be filed next week, not to mention the first subpoena in the matter being sent to Secretary of State Mike Pompeo on Friday.

The chairmen of the Foreign Affairs, Intelligence and Oversight and Reform committees gave Pompeo until Oct. 4 to hand over documents about Trump's July phone call with Ukraine President Zelensky.

The chairmen – Rep. Eliot Engel, D-N.Y.; Rep. Adam Schiff, D-Calif.; and Rep. Elijah Cummings, D-Md. – also plan depositions for five State Department officials over the break: (more on these players below)

•Oct. 2: Ambassador Marie “Masha” Yovanovitch, former ambassador to Ukraine.

•Oct. 3: Kurt Volker, a special representative for Ukraine who played a role arranging meetings between Giuliani and Zelensky’s representatives.

•Oct. 7: Deputy Assistant Secretary George Kent.

•Oct. 8: Counselor T. Ulrich Brechbuhl, who listened to the Ukraine call, according to the whistleblower complaint.

•Oct. 10: Ambassador Gordon Sondland, ambassador to the European Union.

Along with the depositions, which will be taken in private, the House Intelligence Committee also scheduled a hearing on Oct. 4 with Michael Atkinson, the inspector general for the intelligence community, who received the whistleblower's complaint about Trump and deemed it credible and urgent. The hearing will also take place behind closed doors.

Other hearings could be scheduled but Schiff told reporters Friday the panel has to determine who else will testify voluntarily and who will require a subpoena.

All of the movement in Washington will happen as most of Congress is back home on a two-week break. Some lawmakers voiced concern about the timing of the recess, noting that getting to the bottom of this was urgent, momentum was building on the investigation and leaving the Capitol could shift focus.

But, House leadership said the break was an important chance for lawmakers to explain to their constituents what was happening and why, especially in swing districts and for members who flipped seats from conservative grasp in the midterm election.

"I think it's very important that members go home to their constituents and explain what they are thinking," said House Majority Leader Steny Hoyer, D-Md. "This is a matter of grave importance and the American people need to understand what is occurring."

It's also a chance to possibly sway public opinion on the issue as voters remain fairly split on impeaching Trump.

Who are lawmakers questioning?

Lawmakers have a whole host of questions and as they learn more, the questions only seem to grow.

Members of the House Intelligence Committee say some of their priorities are: identifying the estimated dozen officials who were on Trump's telephone call with the Ukrainian president and questioning them, getting additional documents about the phone call, talking with those officials mentioned in the whistleblower complaint, including the officials in the White House who were troubled by the president's conduct and hearing from current and former intelligence officials, who could outline whether notes were handled differently for the Ukraine call.

The White House has acknowledged that a summary of the call was placed into a highly secure system usually reserved for classified information pertaining to extremely sensitive national security matters.

For now, the House has scheduled a series of depositions and one hearing with some of the officials wrapped up in the scandal. Here's more about them:

• Marie “Masha” Yovanovitch: Yovanovitch is a career diplomat and the former U.S. ambassador to Ukraine. She was pulled from her post in May after working years under both Republican and Democratic administrations. Trump called Yovanovitch "bad news" in his July phone call with the Ukrainian president, which followed reports in conservative media that Yovanovitch was disloyal to Trump. She is scheduled to be deposed by Congress on Oct. 2

• Kurt Volker: Volker was a special representative for Ukraine and played a role arranging meetings between Giuliani and Zelensky’s representatives. He resigned on Friday after his name was mentioned in the whistleblower complaint and Giuliani posted private text messages, showing Volker introduced him to a top adviser to the Ukrainian president. The whistleblower complaint also notes that Volker tried to "contain the damage" Giuliani was doing in his efforts to uncover wrongdoing by Biden. He is scheduled to be deposed by Congress on Oct. 3.

•George Kent: Kent is the Deputy Assistant Secretary in the European and Eurasian Bureau at State Department. His job entails, among other things, overseeing policy toward Ukraine. He previously worked as an anti-corruption coordinator for the State Department that specifically targeted Europe. He spoke about the delay in releasing military aid to Ukraine, explaining to Voice of America that it was due to "some issues" with the "the U.S. budgetary process" but that they were "being sorted out." The delayed aid is one of the things House Democrats are investigating as to whether there was a quid pro quo with Trump giving the aid in return for an investigation into Biden. He is scheduled to be deposed by Congress on Oct. 7.

• T. Ulrich Brechbuhl: Brechbuhl works as the Counselor of the State Department, meaning he provides strategic guidance to the Secretary of State on foreign policy, diplomacy and public outreach. He is said to be one of the officials who was on the call as Trump spoke to Ukraine's president, according to the whistleblower complaint. He is scheduled to be deposed by Congress on Oct. 8.

• Gordon Sondland: Sondland is the U.S. ambassador to the European Union. The whistleblower said Sondland, along with Volker, had met with Giuliani to try to "contain the damage" his efforts on Biden were having on U.S. national security. The whistleblower said Volker and Sondland also met with Ukrainian officials to help them navigate the "differing messages" they were getting through official U.S. government channels and Giuliani's private outreach. He is scheduled to be deposed by Congress on Oct. 10.

Michael Atkinson: The House has scheduled a private hearing on Oct. 4 with Atkinson, the inspector general for the intelligence community. Atkinson was the official who received the whistleblower and found it to be credible and of urgent concern. He recommended that the be shared with lawmakers, leading him to clash with his boss, acting Director of National Intelligence Joseph Maguire, who overruled this determination. The complaint was later shared with Congress and the public after the impasse was made public.