President Trump Friday attacked the House impeachment inquiry, saying since there was no quid pro quo, there’s no case.

In a series of tweets related to testimony Thursday by former special envoy to Ukraine Kurt Volcker, Trump quoted Republican Reps. Mark Meadows of North Carolina and Lee Zeldin of New York as saying no pressure was placed on Ukraine to find or manufacture evidence of corruption against former Vice President Joe Biden, one of the leading contenders for the 2020 Democratic nomination.

Trump delayed nearly $400 million in military aid to Ukraine just days before his July 25 phone call to President Volodymyr Zelensky during which Trump asked Zelensky for a “favor.” Trump never explicitly said the aid was dependent on Zelensky’s cooperation.

Ukraine has been fighting Russia-backed separatists for the five years since Moscow seized Ukraine’s Crimea region.

Ukraine’s top prosecutor said Friday he would review previous investigations into whether Biden tried to tank an investigation into the natural gas company on whose board his son, Hunter, served. Prosecutor General Ruslan Ryaboshapka said he would review 15 cases, including those in which Trump was interested.

“No foreign or domestic politicians, officials or people who are not officials called me and tried to influence my decisions on specific criminal proceedings,” Ryaboshapka told a news conference. He said if any laws were violated, appropriate action would be taken.

The impeachment inquiry centers on whether Trump applied undue pressure on Ukraine to initiate investigations into Biden and election meddling. Biden has denied any wrongdoing.

Friday is the deadline for Secretary of State Mike Pompeo, who this week confirmed he listened in on the July 25 call, to turn over subpoenaed documents to the impeachment inquiry. Pompeo has objected to the demand. He was out of Washington as the deadline approached, traveling in Europe.

Mike Atkinson, the inspector general for the intelligence community, was scheduled to testify Friday behind closed doors about his investigation of the whistleblower complaint that triggered the impeachment investigation. He had labeled it “urgent” and “credible,” but it was not turned over to Congress in a timely manner as required by law.

In other impeachment developments:

The chairmen of the House Foreign Affairs, Intelligence and Oversight committees released a document that excerpted text messages among government officials involved in the U.S.-Ukraine relationship. In two instances, the officials indicated they were aware they may have been crossing lines, requesting phone calls so there would be no digital trail.

The texts indicate Trump and his personal attorney, Rudy Giuliani, wanted Volcker and European Union Ambassador Gordon Sondland to convince Ukraine to gin up evidence Biden wanted Ukraine to fire its general prosecutor to protect Biden’s son, and to tie the 2016 hacking into the Democratic National Committee’s emails to Ukraine rather than Russia. Volcker texted that if Zelensky agreed to an investigation, he would be invited to the White House.

Volcker also wrote a statement to be delivered by Zelensky announcing an investigation that Sondland responded was “perfect.”

Sondland requested a phone call, rather than texted response, when asked whether releasing military aid to Ukraine and the White House meeting was conditioned on the investigations.

Elsewhere, CNN has rejected a pair of Trump campaign ads it described as “demonstrably false.” Trump Communications Director Tim Burtaugh responded by calling the network a “Democrat public relations firm” and accused it of protecting Biden.

The first ad suggests Trump is being scrutinized unfairly and claims Biden offered Ukraine $1 billion to fire its prosecutor for looking into “his son’s company.” The second ad describes the impeachment inquiry as a coup aimed at undoing the results of the 2016 presidential election.