US Secretary of State Mike Pompeo speaks during a joint press conference with Italy
PHOTO: Fabio Frustaci/ANSA/AP
US Secretary of State Mike Pompeo speaks during a joint press conference with Italy's Foreign Minister Luigi Di Maio (not pictured) following their meeting at Villa Madama in Rome on October 2, 2019 . ANSA/FABIO FRUSTACI (ANSA via AP)
Now playing
01:10
Mike Pompeo addresses defying subpoena deadline
US President Joe Biden speaks about the 50 million doses of the Covid-19 vaccine shot administered in the US during an event commemorating the milestone in the Eisenhower Executive Office Building in Washington, DC, February 25, 2021. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)
PHOTO: Saul Loeb/AFP/etty Images
US President Joe Biden speaks about the 50 million doses of the Covid-19 vaccine shot administered in the US during an event commemorating the milestone in the Eisenhower Executive Office Building in Washington, DC, February 25, 2021. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)
Now playing
02:28
Axelrod explains the message Biden is sending with strike
WASHINGTON, DC - FEBRUARY 13: Senate Minority Leader Mitch McConnell (R-KY) walks from his office to the Senate Chamber for the fifth day of former President Donald Trump
PHOTO: Chip Somodevilla/Getty Images
WASHINGTON, DC - FEBRUARY 13: Senate Minority Leader Mitch McConnell (R-KY) walks from his office to the Senate Chamber for the fifth day of former President Donald Trump's impeachment trial at the U.S. Capitol on February 13, 2021 in Washington, DC. House impeachment managers asked the senate Saturday for the ability to question witnesses as part of the trial. (Photo by Chip Somodevilla/Getty Images)
Now playing
02:07
McConnell says he'd support Trump as GOP nominee
The Pentagon, the headquarters of the US Department of Defense, located in Arlington County, across the Potomac River from Washington, DC is seen from the air January 24, 2017.  / AFP PHOTO / Daniel SLIM        (Photo credit should read DANIEL SLIM/AFP via Getty Images)
PHOTO: Daniel Slim/Getty Images
The Pentagon, the headquarters of the US Department of Defense, located in Arlington County, across the Potomac River from Washington, DC is seen from the air January 24, 2017. / AFP PHOTO / Daniel SLIM (Photo credit should read DANIEL SLIM/AFP via Getty Images)
Now playing
05:24
US carries out airstrikes on Iran-backed militia groups
The exterior of the U.S. Capitol building is seen at sunrise on February 8, 2021 in Washington, DC. The Senate is scheduled to begin the second impeachment trial of former U.S. President Donald J. Trump on February 9.
PHOTO: Sarah Silbiger/Getty Images
The exterior of the U.S. Capitol building is seen at sunrise on February 8, 2021 in Washington, DC. The Senate is scheduled to begin the second impeachment trial of former U.S. President Donald J. Trump on February 9.
Now playing
01:57
Senate parliamentarian rules against minimum wage increase in relief bill
Now playing
03:56
Marjorie Taylor Greene's challenger explains decision to run
PHOTO: CNN
Now playing
03:44
Acting US Capitol Police chief explains 'operational challenges' from January 6 riot
Rep. Marie Newman (D-IL) speaks with CNN
PHOTO: CNN
Rep. Marie Newman (D-IL) speaks with CNN's Alisyn Camerota.
Now playing
07:17
Lawmaker reacts to Rep. Taylor Greene's tweet on her transgender daughter
Connolly
PHOTO: CNN
Connolly
Now playing
03:51
'I will not be lectured' on bipartisanship: Lawmaker fires back at Jim Jordan
US President Donald Trump speaks to the press from the South Lawn of the White House after announcing and initial deal with China in Washington, DC, prior to departing to Lake Charles, Louisiana to hold a campaign rally on October 11, 2019.
PHOTO: NICHOLAS KAMM/AFP/Getty Images
US President Donald Trump speaks to the press from the South Lawn of the White House after announcing and initial deal with China in Washington, DC, prior to departing to Lake Charles, Louisiana to hold a campaign rally on October 11, 2019.
Now playing
02:28
Romney says he's 'pretty sure' Trump will win 2024 nomination if he runs
Now playing
02:04
Senate moderates create obstacle for Biden's nominee
This picture taken 26 December 2011 shows the Pentagon building in Washington, DC.  The Pentagon, which is the headquarters of the United States Department of Defense (DOD), is the world
PHOTO: Staff/AFP/Getty Images
This picture taken 26 December 2011 shows the Pentagon building in Washington, DC. The Pentagon, which is the headquarters of the United States Department of Defense (DOD), is the world's largest office building by floor area, with about 6,500,000 sq ft (600,000 m2), of which 3,700,000 sq ft (340,000 m2) are used as offices. Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon. (Photo credit should read STAFF/AFP via Getty Images)
Now playing
04:30
Pentagon report gives insight on White supremacists in active military
Now playing
03:57
GOP senator continues to push riot conspiracy theory
Now playing
02:08
Cabinet secretary explains why he took on challenging role
Rep. Debra Haaland (D-NM), President Joe Biden
PHOTO: Leigh Vogel/Pool/Getty Images
Rep. Debra Haaland (D-NM), President Joe Biden's nominee for Secretary of the Interior, testifies during her confirmation hearing before the Senate Committee on Energy and Natural Resource, at the U.S. Capitol on February 24, 2021 in Washington, DC.
Now playing
00:59
'We need to work together': Haaland responds to question on blind loyalty
Now playing
01:35
Laughter follows awkward moment between GOP leaders
(CNN) —  

House Democrats on Monday expanded their impeachment inquiry with subpoenas to the Pentagon and Office of Management and Budget tied to the freezing of foreign aid to Ukraine.

The newest subpoenas broaden the House’s impeachment investigation into President Donald Trump’s interactions with Ukraine into new corners of the federal government. They follow subpoenas that have already been issued to the State Department and White House, as well as the President’s personal attorney Rudy Giuliani, as Democrats seek to rapidly gather information as they consider whether to impeach the President.

The committees have also requested information from Vice President Mike Pence as part of the probe.

The subpoenas to the Pentagon and OMB are related to the decision to hold up foreign aid to Ukraine, which came at the same time that Giuliani and Trump were pushing for Ukraine to launch an investigation into the 2016 US election, then-Vice President Joe Biden and his son, Hunter Biden. There is no evidence of wrongdoing in relation to Ukraine by the Bidens.

LIVE UPDATES: The latest on the Trump impeachment inquiry

“The enclosed subpoena demands documents that are necessary for the Committees to examine this sequence of these events and the reasons behind the White House’s decision to withhold critical military assistance to Ukraine that was appropriated by Congress to counter Russian aggression,” the chairmen wrote.

It’s not clear how the agencies will respond to the subpoenas. The State Department missed a Friday deadline to turn over documents that Democrats’ subpoenaed, and the White House has indicated that it will not comply with the subpoena issued on Friday, arguing that the House needs to first take a full vote on authorizing an impeachment inquiry.

Last week, however, the Pentagon’s chief legal officer requested that Defense Department agencies identify, preserve and collect any and all documents relating to the provision of security assistance to Kiev.

Giuliani associates could get subpoenas

More subpoenas could be on the way, too.

Democrats have requested information from three Giuliani associates — Lev Parnas, a Ukrainian-American businessman who worked with Giuliani; Igor Fruman, a business partner of Parnas; and Semyon “Sam” Kislin, a former aide to Giuliani — and they’re warning they will subpoena three Giuliani associates if they do not comply with their requests for documents and depositions.

They have not cooperated so far, a source said. Two were supposed to testify at the end of this week and another next week. And the deadline to turn over documents is Monday.

“While we have engaged with counsels for these witnesses, they have so far refused to agree to testify or turn over relevant documents - if they continue to fail to comply, they will be served with subpoenas in short order,” an official working on the impeachment inquiry said.

John Dowd, who is representing Parnas and Fruman, wrote in a letter to the committees that some of the information they’re seeking is protected by attorney-client privilege, and a review of the material cannot be conducted in just the week given to comply with the request. He said he expected to meet with them this week and review the documents requested, but said that responding to the committees “will take some time.”

“Your request for documents and communications is overly broad and unduly burdensome. The subject matter of your requests is well beyond the scope of your inquiry,” Dowd wrote. “This, in combination with requiring immediate responses, leads me to the inescapable conclusion that the Democratic committee members’ intent is to harass, intimidate and embarrass my clients.”

Sondland testifying this week

The Democrats’ investigation stems from a whistleblower alleging the President solicited help from Ukraine to investigate a political rival in his July 25 call Ukrainian President Volodymyr Zelensky. The complaint also notes that foreign aid to Ukraine had been suspended around the same time.

The aid was subsequently released by the Trump administration in September, but Democrats are now probing the reasons is was held up in the first place.

In text messages provided by former US special envoy Kurt Volker to Congress last week, senior US diplomat in Ukraine Bill Taylor expressed alarm that aid was being frozen, suggesting it was tied to the request for an investigation into Biden.

“Are we now saying that security assistance and WH meeting are conditioned on investigations?” Taylor texted US Ambassador to the European Union Gordon Sondland on September 1.

“As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign,” Taylor texted a week later.

Sondland responded to Taylor’s second text that he was “incorrect” about Trump’s intentions.

“Bill, I believe you are incorrect about President Trump’s intentions,” Sondland said. “The President has been crystal clear no quid pro quo’s of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign.”

But the texts show how the Ukrainians’ efforts to secure a meeting between Trump and Zelensky was in fact linked to the opening of an investigation ahead of the July 25 phone call.

Sondland appears behind closed doors before the House Intelligence, Oversight and Foreign Affairs Committees on Tuesday.

This story has been updated with additional developments Monday.

CNN’s Manu Raju and Gloria Borger contributed to this report.