WASHINGTON — Democrats on Tuesday issued a subpoena to U.S. ambassador to the European Union Gordon Sondland hours after he failed to show up for a scheduled deposition before three House committees.

The subpoena seeks Sondland's testimony as well as documents related to President Donald Trump’s apparent efforts to have Ukrainian officials investigate former Vice President Joe Biden and his son.

Issued by House Intelligence Committee Chairman Adam Schiff, D-Calif., in consultation with House Oversight Committee Chairman Elijah Cummings, D-Md., and House Foreign Affairs Committee Chairman Eliot Engel, D-N.Y., the subpoena called on Sondland to produce documents by Oct. 14.

Text messages provided to Congress last week show Sondland and another ambassador worked to persuade Ukraine to publicly commit to investigating Trump’s political opponents and explicitly linked the inquiry to whether Ukrainian President Volodymyr Zelenskiy would be granted an official White House visit.

A letter from the three chairmen accompanying the subpoena also called on the U.S. diplomat to appear for a deposition on Oct. 16 after he failed to show up on Tuesday.

The chairmen warned Sondland that if he fails or refuses to comply with the subpoena, "including at the direction or behest of the president, the White House or State Department," it would "constitute further evidence of obstruction of the House’s impeachment inquiry and may be used as an adverse inference against you and the president."

This came after the State Department directed Sondland not to appear for a scheduled deposition to deliver closed-door testimony on Tuesday morning before lawmakers on the three committees.

"In light of Secretary [Mike] Pompeo’s direct intervention to block your appearance before our Committees, we are left with no choice but to compel your appearance at a deposition pursuant to the enclosed subpoena,” the chairmen wrote in the letter.

Some of the documents and communications Democrats have requested in the subpoena encompass meetings between Trump and Zelenskiy and phone calls between the two leaders on certain dates. They also asked for more information regarding the U.S. delegation to the Ukrainian president’s inauguration in May and a potential visit of Zelensky to the U.S. for an Oval Office meeting with Trump, among other things.

"Secretary Pompeo’s obstruction of the House’s impeachment inquiry does not alleviate you of your independent legal obligation to produce to the Committees any responsive documents in your personal possession, custody, or control," the chairmen wrote to Sondland.

"There is no valid basis to withhold documents from the Committees by relying on instructions from Secretary Pompeo, who is a fact witness in this inquiry and who is currently defying his own duly issued subpoena for documents — particularly if the Department’s goal is to block the Committees from gaining access to your documents prior to your testimony."