The House Intelligence Committee has subpoenaed President Donald Trump's lawyer Rudy Giuliani for Ukraine-related documents as part of their impeachment inquiry.

"Pursuant to the House of Representatives’ impeachment inquiry, we are hereby transmitting a subpoena that compels you to produce the documents set forth in the accompanying schedule by October 15, 2019," a joint letter from House Intelligence chair Adam Schiff, Oversight chair Elijah Cummings and Foreign Affairs chair Eliot Engel to Giuliani says.

The lawmakers noted that Giuliani has acknowledged in several recent interviews that he had asked a Ukrainian prosecutor for information about former Vice President Joe Biden.

"In addition to this stark admission, you stated more recently that you are in possession of evidence—in the form of text messages, phone records, and other communications—indicating that you were not acting alone and that other Trump Administration officials may have been involved in this scheme," the letter, which was sent Monday, says.

"Our inquiry includes an investigation of credible allegations that you acted as an agent of the President in a scheme to advance his personal political interests by abusing the power of the Office of the President. A growing public record, including your own statements, indicates that the President, you, and others appear to have pressed the Ukrainian government to pursue two politically motivated investigations," the letter says.

They demanded that the former New York City mayor turn over all of those documents by Oct. 15.

"Your failure or refusal to comply with the subpoena, including at the direction or behest of the President or the White House, shall constitute evidence of obstruction of the House’s impeachment inquiry and may be used as an adverse inference against you and the President," the letter says.

Giuliani told NBC News later on Monday that he hadn't made a decision yet on whether to comply with the subpoena, which he referred to as part of a "partisan witch hunt."

The White House did not respond to a request for comment.

I have received a subpoena signed only by Democrat Chairs who have prejudged this case. It raises significant issues concerning legitimacy and constitutional and legal issues including,inter alia, attorney client and other privileges. It will be given appropriate consideration. — Rudy Giuliani (@RudyGiuliani) September 30, 2019

Schiff told "Meet the Press" on Sunday that the House is working "urgently" to investigate all facets of Trump's dealings with Ukraine, including whether the president committed an impeachable offense when he brought up Biden during a July phone conversation with the Ukrainian president. The House is also looking into whether Giuliani's overtures were proper and whether the White House was using almost $400 million in frozen aid to Ukraine as leverage.

The document does not seek to call Giuliani to testify, which is something the former mayor said he'd "consider." Giuliani has launched blistering attacks against Schiff on Twitter in recent days, calling him "prejudiced," "dishonest" and "a disgrace."

The committee is asking for documents and testimony from three business associates of Giuliani's in the next two weeks — Lev Parnas, Igor Fruman and Semyon Kislin.