WASHINGTON (AP) — Congressional Democrats on Monday pressed their demands for full disclosure of a whistleblower's complaint about President Donald Trump and intensified calls for impeachment. Trump insisted anew he did nothing wrong in his conversation with Ukraine's leader that is at the center of the complaint.

Republican lawmakers remained largely silent amid the reports that the president 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.

Trump acknowledged the phone call and said he didn't want to give money to Ukraine — if there were corruption issues. His comments raised further questions about whether he improperly used his office to pressure the country into investigating the former vice president and his family as a way of helping his own reelection prospects.

"It's very important to talk about corruption," Trump told reporters as he opened meetings at the United Nations. "If you don't talk about corruption, why would you give money to a country that you think is, is corrupt?"

Trump has sought, without evidence, to implicate Biden and his son Hunter in the kind of corruption that has long plagued Ukraine. Hunter Biden served on the board of a Ukrainian gas company at the same time his father was leading the Obama administration's diplomatic dealings with Kyiv. Though the timing raised concerns among anti-corruption advocates, there has been no evidence of wrongdoing by either the former vice president or his son.

The matter is under new scrutiny following the whistleblower's mid-August complaint, which followed Trump's July 25 call with Ukraine President Volodymyr Zelenskiy. The person who filed the complaint did not have firsthand knowledge of the call, according to a person familiar with the matter.

Lawmakers are demanding details of the complaint, but the acting director of national intelligence has refused to share that information, citing presidential privilege.

Later Monday, Trump denied telling the Ukraine president that his country would only get U.S. aid if it investigated Biden's son. "I didn't do it," he said, adding that he hoped a transcript would be made available to demonstrate his innocence.

Meanwhile, Senate Democratic Leader Chuck Schumer of New York called on Republican Majority Leader Mitch McConnell to investigate the whistleblower's complaint. In a letter to McConnell, he said that the Republicans' "see no evil, hear no evil" attitude toward the president's actions "is unacceptable and must change."

"In the face of this dire warning and the Trump administration's effort to cover it up, the Republican-led Senate has remained silent and submissive, shying away from this institution's constitutional obligation to conduct oversight," Schumer wrote in the letter.

Still, Democrats themselves remained divided on moving forward with an effort to impeach Trump. House Speaker Nancy Pelosi has resisted calls for impeachment for other allegations of Trump transgressions, and so far she is sticking with her position that Congress must not start formal proceedings unless the American public demands it. She has frequently said she doesn't believe that Americans are there yet.

However, Pelosi said Sunday that unless the administration provides more information to Congress by a scheduled Thursday hearing at the intelligence committee, its officials "will be entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation."

More than half the House Democrats have said they support impeachment, and more are expected this week to publicly favor such an investigation, but others worry it is too politically divisive and would only alienate more centrist voters.

Rep. Jim Himes, D-Conn., said the Trump administration's "disregard for the law has reached a boiling point." He predicted the pressure for impeachment "will rise significantly."

The president said over the weekend that his phone call with Zelenskiy was "congratulatory" and focused on corruption in the East European nation. In his remarks to reporters, he then raised Biden as an example.

A person familiar with the matter has told The Associated Press that Trump urged Zelenskiy to investigate Hunter Biden. The person wasn't authorized to discuss the issue publicly and spoke on the condition of anonymity.

Hunter Biden was hired by the Ukrainian gas company Burisma Holdings in April 2014, two months after Ukraine's Russia-friendly former president was ousted by protesters and as Biden's father was heavily involved in U.S. efforts to support the new pro-Western government. The move immediately raised concerns that the Ukrainian firm, whose owner was a political ally of the ousted president, was seeking to gain influence with the Obama administration.

Schumer called on McConnell to take five specific steps to probe the current situation, including issuing a subpoena to compel the whistleblower's complaint to be delivered to Congress. He said Republicans should tell the White House to release transcripts of Trump's conversation with the Ukraine president and identify who in the White House sought to delay $250 million in aid to Ukraine.

Trump said on Sunday he would look into releasing details or a transcript of the call but stressed that foreign leaders should feel free to speak frankly with an American president without fear that the details of their conversations will later be disclosed.

South Carolina Sen. Lindsey Graham, one of the president's closest allies, urged Trump on Monday to be "as transparent as possible" and predicted the White House transcript would be released.

"I believe that President Trump is going to blow you away with his willingness to disclose and be transparent about this phone call, because I think he did nothing wrong and he has nothing to hide," Graham said on the Hugh Hewitt radio show.

Trump and Zelenskiy plan to meet on the sidelines of the U.N. General Assembly this week.

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Associated Press writers Matthew Daly and Michael Balsamo in Washington contributed