WASHINGTON (AP) — President Donald Trump suggested that he raised former Vice President Joe Biden and Biden's son in a summer phone call with Ukraine's new leader, as Democrats pressed for investigations into whether Trump improperly used his office to try to dig up damaging information about a political rival.

Trump told reporters that the July 25 call with Ukrainian President Volodymyr Zelenskiy was "congratulatory" and focused on corruption in the East European nation. In his remarks to reporters, he then raised Biden as an example, although there is no evidence of wrongdoing by Biden or his son Hunter, who was on the board of a Ukrainian gas company.

"It was largely the fact that we don't want our people, like Vice President Biden and his son, creating to the corruption already in the Ukraine," Trump said as he left the White House for a trip to Texas.

Biden, who is among the front-runners for the Democratic presidential nomination, accused Trump of making a baseless political smear.

The matter has sparked a fierce debate over whether Trump misused his office for political gain and whether his administration is withholding from Congress critical information about his actions. The incident is part of a whistleblower complaint, but the acting director of national intelligence, Joseph Maguire, has refused to share details with lawmakers, citing presidential privilege.

Democratic House Speaker Nancy Pelosi, who has resisted calls for impeachment for other alleged Trump transgressions, said Sunday that unless Maguire provides information to Congress, administration officials "will be entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation."

Another impeachment holdout, the chairman of the House Intelligence Committee, Rep. Adam Schiff, D-Calif., said Sunday on CNN's "State of the Union" that "we may very well have crossed the Rubicon here."

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.

"Ukraine's got a lot of problems," Trump said at the White House. "The new president is saying that he's going to be able to rid the country of corruption and I said that would be a great thing. We had a great conversation. We had a conversation on many things."

Hunter Biden was hired by the Ukrainian gas company Burisma Holdings in April 2014, two months after Ukraine's Russia-friendly president was ousted by protesters and as his father was heavily involved in U.S. efforts to support the new pro-Western government and its pledge to fight corruption. The hiring of the younger Biden 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.

Two years later, Joe Biden pressured the Ukrainian government to fire the prosecutor general, who was accused by many in Ukraine and in the West of being soft on corruption. Trump has claimed that the prosecutor, who had led an investigation into Burisma's owner, "was after" Hunter Biden and the vice president was trying to protect his son. There is no evidence of this.

Trump insisted he said "absolutely nothing wrong" in the call to Zelenskiy. He did not answer directly when asked whether he would release a transcript of the conversation to the public.

After arriving in Texas , Trump told reporters he will 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. Trump said if Ukraine released its own transcript it would be the same as his version of the call.

White House press secretary Stephanie Grisham, while acknowledging that there can be "10 to 20 people" listening in on such calls, reiterated Trump's position that foreign leaders need to be able to speak candidly.

"And so I do think that perhaps releasing this kind of a transcript could set a bad precedent," Grisham said on Fox News Channel's "Fox & Friends" on Monday. "He's willing to do it, I think, but there's a lot of other people, lawyers and the such, that may have a problem with it."

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

The Republican president has described the whistleblower as "partisan" but has acknowledged not knowing the identity of the intelligence official who lodged a formal complaint against him with the inspector general for the intelligence community.

The complaint was based on a series of events, including the July 25 call between Trump and Zelenskiy, according to two people familiar with the matter. They were not authorized to discuss the issue by name and were granted anonymity.

In addition, Trump last month placed a freeze on the release on $250 million in military aid to Ukraine without providing an excuse, raising suspicions among his Democratic critics that he was trying to squeeze Zelenskiy. The aid was released before a likely rebuke by the Senate Appropriations Committee.

Biden said in Iowa on Saturday that "Trump deserves to be investigated" for "trying to intimidate a foreign leader, if that's what happened." Biden said Trump was motivated by politics "because he knows I'll beat him like a drum."

A leading Republican senator urged the Justice Department to investigate the "Biden-Ukraine connection."

"We have looked at all things Russia and Trump, his family, everything about his family, every transaction between the Trump campaign and Russia," Sen. Lindsey Graham of South Carolina told Fox News Channel's "Sunday Morning Futures."

Now is the time, he said, to know "what relationships, if any, did Biden world have to the Ukraine."

Michael Atkinson, the U.S. government's intelligence inspector general, has described the whistleblower's Aug. 12 complaint as "serious" and "urgent," but he has not been allowed to turn over the complaint to Congress.

Maguire, the acting intelligence director, has been subpoenaed by Schiff's committee and is expected to testify publicly on Thursday. Maguire and Atkinson also are expected to appear before the Senate Intelligence Committee this week.

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Associated Press writer Jonathan Lemire in New York contributed to this report.