WASHINGTON – This week will be packed with activity in the House impeachment investigation of President Donald Trump as committees subpoena more documents about the administration's dealings with Ukraine and lawmakers depose State Department officials.

The fast-paced developments can be a confusing jumble of foreign names and officials who don’t typically show up in news stories. The key elements focus on Trump urging Ukrainian President Volodymyr Zelensky in a call July 25 to investigate his political rival former Vice President Joe Biden while crucial military aid to that country was frozen. Trump insists he was justified to fight corruption in Ukraine.

Three House panels – Foreign Affairs, Intelligence and Oversight and Reform – subpoenaed the White House and State Department for documents about Ukraine. The panels are interviewing State Department officials and intermediaries who helped Trump’s personal lawyer Rudy Giuliani encourage the investigation of Biden.

Trump called the investigation a witch hunt and vowed to fight all subpoenas. The president called Sunday for the impeachment of House Speaker Nancy Pelosi, D-Calif., and the chairman of the Intelligence Committee, Rep. Adam Schiff, D-Calif., for treason.

More:A visual timeline of the text messages in the Trump-Ukraine affair

Here is a roundup of the players and events this week, although timing for some is in flux:

Monday

A federal judge in New York dismissed Trump’s lawsuit to block Manhattan District Attorney Cyrus Vance from gaining access to eight years of tax returns. Trump filed notice he would appeal the decision. Four House committees are pursuing Trump’s tax returns for evidence of possible corruption in three federal lawsuits.

Three committees – Foreign Affairs, Intelligence and Oversight – subpoenaed the Pentagon and White House Office of Management and Budget for documents about the administration’s temporary freeze on military aid for Ukraine. The administration froze $400 million in aid in July and released the funding in September. Lawmakers said they are exploring reasons for the cutoff. The deadline for the documents is Oct. 15.

The three panels subpoenaed Ukraine documents from Secretary of State Mike Pompeo and Giuliani. The department missed a deadline Friday that the panel set for documents. Pompeo accused lawmakers of bullying department staffers.

Tuesday

Gordon Sondland, U.S. ambassador to the European Union, was scheduled to give a deposition to the three committees, but the Styate Department blocked his appearance. An unidentified whistleblower said Sondland, along with Kurt Volker, the special representative to Ukraine, who gave a deposition Thursday, met with Giuliani to try to "contain the damage" his efforts on Biden hadon U.S. national security.

The whistleblower said Volker and Sondland 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. Texts that the committees released showed Bill Taylor, the top diplomat in Ukraine, asking, "Are we now saying that security assistance and WH meeting are conditioned on investigations?" Sondland texted back, "Call me."

U.S. District Court Judge Beryl Howell scheduled arguments for the House Judiciary Committee’s subpoena for grand jury evidence behind special counsel Robert Mueller’s report on Russian interference in the 2016 election. The committee seeks the evidence for Trump’s possible obstruction of Mueller’s 22-month investigation. The Justice Department opposed the request and said it could jeopardize cases. House Republicans contended the committee doesn’t qualify for grand jury evidence unless the full House votes to authorize an impeachment investigation, but Pelosi said no vote is necessary.

Thursday

The three panels scheduled a deposition with Lev Parnas, a Ukrainian-born businessman who helped introduce Giuliani to a Ukrainian prosecutor who sought to provide dirt on Biden.

Trump scheduled a political rally in Minneapolis. The rally sparked controversy because the police department prohibits officers from wearing their uniforms at political events or in ads. The police union struck back by creating "Cops for Trump" T-shirts.

Friday

The three committees scheduled a deposition with Marie Yovanovitch, a career diplomat and former U.S. ambassador to Ukraine. She was pulled from her post in May after working years under Republican and Democratic administrations. Trump called Yovanovitch "bad news" in his phone call with the Ukrainian president.

The three committees scheduled a deposition with Igor Fruman, a Ukrainian-born business partner of Parnas, who helped introduce Giuliani to the Ukrainian prosecutor.

Trump will rally supporters in Lake Charles, Louisiana. This would be the third event in a week in the state where members of the Trump administration have rallied voters, including Oct. 5 when Vice President Mike Pence was in Kenner and Monday when the president's son Donald Trump Jr. visited Lafayette.

More about the impeachment investigation of President Donald Trump:

Nancy Pelosi has put the Trump impeachment inquiry on a fast track. Here's the plan, timeline and players

What's going on with Trump and Ukraine? And how does it involve Biden and a whistleblower complaint?

Read the full declassified text of the Trump whistleblower complaint