President Donald Trump during a meeting in the Oval Office of the White House, September 16, 2019.

The chairmen of three U.S. House of Representatives Committees threatened to subpoena Secretary of State Mike Pompeo on Monday if he does not provide documents related to President Donald Trump's dealings with Ukraine.

In response, Senate Majority Leader Mitch McConnell said he personally pressured the Trump administration to release U.S. aid to Ukraine this summer, a time when the funding is now under scrutiny with a whistleblower's complaint against the president.

The Republican leader said he did not know the content of the whistleblower's complaint. Trump was reportedly withholding funding for Ukraine as he urged the country's president to investigate his chief political rival, Joe Biden. Trump denied any wrongdoing.

McConnell said he contacted both the Defense Secretary and the Secretary of State this summer to release the funds.

He criticized Democrats for demanding public scrutiny of Trump's actions. He said the Intelligence committee should handle questions in a classified setting.

The chairmen of the House Foreign Affairs, Intelligence and Oversight Committees sent a letter earlier Monday demanding that Pompeo produce information about whether the president and his lawyer, Rudy Giuliani, inappropriately tried to influence the government of Ukraine for political gain.

The heads of the committees threatened subpoenas in the letter if the documents aren't provided by Thursday.

The committees asked for the documents two weeks ago. Since then, it has emerged that Director of National Intelligence Joseph Maguire is holding back a whistleblower complaint from Congress. The AP and other news outlets have reported the complaint is linked to a phone call where Trump pressured Ukraine's leader to investigate Joe Biden's son.

Trump denied that he told the president of Ukraine that his country would only get U.S. aid if they investigated the son of Democratic rival Joe Biden.

During a meeting Monday on the sidelines of the United Nations, Trump said emphatically: "I didn't do it."

He said he hoped people would be able to eventually see a transcript of the call. He says if his critics ever see it, they will be "very disappointed."

Trump said he didn't put "any pressure" on Ukraine to investigate Hunter Biden.

His comments came amid reports he pressured Ukraine's leader to help investigate political rival Joe Biden at the same time the White House was withholding $250 million in aid to the Eastern European nation.

The top Senate Democrat called Majority Leader Mitch McConnell Monday morning to investigate a whistleblower's complaint about President Donald Trump's actions toward Ukraine.

Chuck Schumer said in a letter to McConnell that the Republicans' "see no evil, hear no evil" attitude toward the president's actions "is unacceptable and must change."

The New York Democrat called on McConnell to take five specific steps to probe the situation, including issuing a subpoena to compel the whistleblower's complaint to be delivered to Congress.

Schumer also said Republicans should tell the White House to release transcripts of Trump's conversation with the Ukrainian president and identify who in the White House sought to delay $250 million in aid to Ukraine. Trump reportedly asked the foreign leader to investigate his chief political rival, Joe Biden.