President Donald Trump on Sunday acknowledged that he discussed former Vice President Joe Biden during a July phone call with Ukrainian President Volodymyr Zelensky, but denied accusations that he is using the power of his office to hurt a major political rival.

"No quid pro quo, there was nothing," Trump told reporters on the White House South Lawn. "It was a perfect conversation."

The phone call has ignited a political maelstrom in Washington this week as the latest revelation about a months-long effort to get Ukraine to investigate Biden, who is running for president against Trump, and his son. According to the Wall Street Journal and other outlets, Trump pressed the new Ukrainian leader to investigate Hunter Biden's business dealings in Ukraine and whether they affected the former vice president's diplomatic efforts. Because the phone call occurred while Ukraine was still awaiting military aid from the U.S., critics have raised the possibility that Trump was attempting a quid pro quo arrangement.

"I'm not looking to hurt Biden or even hold him to it," Trump said on Sunday, adding, "Now me, on the other hand, my conversation with the new president of Ukraine was perfect."

Trump said that while he discussed the Bidens on the phone call, there was "absolutely nothing wrong" with the conversation.

"The conversation I had was largely congratulatory, with largely corruption, all of the corruption taking place and largely the fact that we don't want our people like Vice President Biden and his son creating the corruption already in the Ukraine and Ukraine has got a lot of problems. 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."

Speaking to reporters later on Sunday in Texas, Trump said he might provide a copy of the transcript to a "respected source," adding "everyone will say" the conversation between him and Ukraine's president was perfectly fine.

"I know when I give pressure," Trump said.

Trump weighed in again Sunday night with a pair of tweets, disputing the Journal report and describing his call with the Ukrainian leader as "nice."

The phone call reportedly led to a whistleblower complaint from within the intelligence community, the existence of which was first revealed earlier this month. The Washington Post reported on Wednesday that the complaint centered around a "promise" that Trump made to a foreign leader. Over the next few days, the Post and other media outlets reported that the complaint involved Ukraine.

The president's focus on Biden and Ukraine comes amid his personal attorney Rudy Giuliani's months-long effort to get Ukraine to further investigate the former vice president, an effort which was aided by the State Department, as NBC News reported last month. The push centers on Biden's 2016 call — widely backed by the international community — for Ukraine to crack down on corruption, including removing a Ukrainian prosecutor, Viktor Shokin, who was seen as ineffective and was later removed by the country's parliament. One of the cases that Shokin was investigating involved Burisma Holdings, a natural gas company whose board at the time included Biden's son.

Earlier this year, Bloomberg News, citing documents and an interview with a former Ukrainian official, reported the Burisma investigation had been dormant for more than a year by the time Biden called for the crackdown on corruption. The then-Ukrainian prosecutor general told the news agency that he found no evidence of wrongdoing by Biden and his son. PolitiFact, meanwhile, reported that it found no evidence to "support the idea that Joe Biden advocated with his son's interests in mind."

Giuliani, as he's noted, learned of the Biden episode through his efforts to have Ukraine examine whether the Democratic National Committee worked in connection with Ukrainian officials to harm Trump's 2016 campaign by releasing damaging information on the president's former campaign chairman, Paul Manafort, who is now serving a lengthy prison sentence as part of Mueller's investigation.

House Democrats have already announced an investigation into Giuliani's Ukrainian efforts. In a CNN interview from Thursday, Giuliani denied asking Ukrainian officials to probe Biden but, moments later, said: "Of course I did."

On Wednesday, Trump is set to meet face to face with Zelensky, on the sidelines of the United Nations General Assembly in New York. In the weeks before the whistleblower complaint became public, the Trump administration froze $250 million in military aid to Ukraine for unclear reasons. Then, just before Democrats revealed the existence of the whistleblower complaint, the administration released the hold on Ukrainian military aid.

On Saturday, Ukrainian Foreign Minister Vadym Prystaiko said he didn't think Trump pressured Zelensky, a former comedian, during their July phone call.

"I know what the conversation was about, and I think there was no pressure," he said. "There was talk, conversations are different, leaders have the right to discuss any problems that exist. This conversation was long, friendly, and it touched on a lot of questions, including those requiring serious answers."

Meanwhile, acting Director of National Intelligence Joseph Maguire has been withholding the whistleblower complaint from Congress, which has demanded his testimony and the complaint. The intelligence community's inspector general regarded the complaint as an "urgent concern" that the law required him to provide to the congressional intelligence committees, but the Justice Department ruled the complaint did not need to be turned over. House Speaker Nancy Pelosi on Sunday implored Maguire to release the complaint, saying that further stonewalling would be "entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation."

Trump spent much of the past few days denying any wrongdoing as part of his conversation with Ukraine, initially saying Thursday that he knows many people listen into his phone calls, asking "is anybody dumb enough to believe that I would say something inappropriate with a foreign leader while on such a potentially 'heavily populated' call" and insisting that he "would only do what is right anyway, and only do good for the USA!"

On Saturday though, the president appeared to question whether someone on the phone call was spying on him, quoting analysis from a Fox News analyst. The president deemed this new scandal "the Ukraine Witch Hunt," echoing language he used regarding former special counsel Robert Mueller's investigation into Russian interference in the 2016 presidential election, if Trump or associates conspired with Russian officials and whether Trump sought to obstruct the probe.

Democrats have been up in arms in recent days about the allegations. Speaking to reporters in Iowa on Saturday, Biden said "Trump's doing this because he knows I'll beat him like a drum and he's using the abuse of power and every element of the presidency to try to do something to smear me." Biden called Trump "a serial abuser" whose call to investigate the former vice president's family "crosses the line, this crosses the line."

Sen. Elizabeth Warren, D-Mass. and a 2020 presidential contender, said in Iowa Saturday that Trump "has solicited another foreign government to attack our election system, it is time for us to call out this illegal behavior and start impeachment proceedings right now."

And on Twitter, Rep. Alexandria Ocasio-Cortez, D-N.Y., said: "At this point, the bigger national scandal isn’t the president’s lawbreaking behavior — it is the Democratic Party’s refusal to impeach him for it."

A senior aide to a House Democrat told NBC News in an email: "I have always thought that the pro-impeachment crowd made a big tactical mistake by focusing on Pelosi, she is just expressing her sense of what the Caucus has the votes to do."

"In the same vein, the crucial question with Ukraine is how people who haven’t previously supported impeachment feel about it," the aide added.

Ukraine was also the topic of the day on Sunday's political talk shows. Speaking with NBC's "Meet the Press," Sen. Pat Toomey, R-Pa., said Congress should "find out why" the administration withheld aid from Ukraine, adding, "It is not appropriate for any candidate" to "ask for assistance from a foreign government." Sen. Chris Murphy, D-Conn., told the program that if a U.S. president "is asking another foreign leader to interfere in an American election … then there has to be consequences" regardless of if there was a direct quid pro quo."