Democratic presidential candidate Joe Biden on Saturday urged for an investigation into a call in July between President Donald Trump and Ukrainian President Volodymyr Zelensky in which Trump allegedly pressed Zelensky eight times into investigating financial activities of Biden's son in Ukraine.

"This appears to be an overwhelming abuse of power. To get on the phone with a foreign leader who is looking for help from the United States and ask about me and imply things… this is outrageous," Biden said while campaigning in Iowa.

Biden added that Trump is abusing his power as president in order to smear his image.

Trump has said that the "Fake News Media " has fabricated a story about "a perfectly fine and routine conversation I had with the new President of Ukraine."

The Washington Post reported last week that a Trump call with a foreign leader had involved Trump making a "promise" that was so alarming that an official in the intelligence community had to file an official whistleblower complaint. The Wall Street Journal reported Friday that a source said Trump had told Zelensky "that he should work with [Trump's lawyer Rudy Giuliani] on Biden, and that people in Washington wanted to know."

Giuliani reportedly met with top Ukrainian officials in the summer about an investigation.

The Trump administration had been investigating whether Hunter Biden broke any laws while serving on the board of the Burisma Group, an energy company in Ukraine. There had been suspicion that Joe Biden used his position as vice president in 2016 to try to prevent a Ukrainian corruption investigation into Hunter Biden. The Ukrainian prosecutor general has said he has found no evidence into any wrongdoing by Joe Biden or Hunter Biden.

“I do not want Ukraine to again be the subject of U.S. presidential elections,” Ukraine's current prosecutor Yuriy Lutsenko told Bloomberg in May. “Hunter Biden did not violate any Ukrainian laws -- at least as of now, we do not see any wrongdoing. A company can pay however much it wants to its board.”

This summer, $250 million in military aid to Ukraine was held up by the Trump administration in order to review the funds. There are concerns that Trump used aid money as a reward for the Ukrainian government digging up compromising information on Hunter Biden.