U.S. Sen. Chris Murphy called on fellow lawmakers to open a new investigation into President Donald Trump on Friday amid reports Trump repeatedly urged the president of Ukraine to investigate former Vice President Joe Biden's son.

The revelation comes as some Congressional leaders fought this week to gain access to a whistleblower complaint that reportedly concerns Trump's conversations in late July with new Ukrainian President Volodymyr Zelensky.

Earlier this year Murphy requested that the Senate Foreign Relations Committee look into reports that Rudolph Guliani, one of the president's attorneys, was meeting with Ukrainian leaders to try to convince them to investigate the son of Biden, a frontrunner in the Democratic primary to challenge Trump's reelection bid next year.

Trump then asked Zelensky eight times during a phone call to work with Giuliani on the investigation into the younger Biden's energy company, although Ukrainian officials have no evidence of wrongdoing, the Wall Street Journal reported.

"New reports about the President's potential direct involvement in that effort, including reported unspecified commitments made to the President of Ukraine, significantly heighten national security concerns and require that the Committee immediately hold a hearing to investigate these matters and their consequences for U.S. foreign policy," Murphy wrote in a letter to committee chairman Sen. Jim Risch, R-Idaho.

Both Murphy and U.S. Rep. Jim Himes called on Republicans to "put country, not party, first" to investigate the new allegations.

"If this turns out to be true, that Trump asked a country relying on us for military aid to investigate his political opponents, well, I wonder if my ?[GOP?] colleagues will put country before party," Himes wrote in a tweet. "Spoiler alert: No."

The details reported Friday are the most specific details to emerge yet from the still-secret whistleblower complaint last month that the Trump administration has refused to provide to lawmakers and has become the center of a heated fight in the U.S. Capitol. Democratic lawmakers, including Murphy and Himes, have seized on the unraveling story to demand new accountability on the president, who has denied any inappropriate communications with foreign leaders.

"It doesn't matter what I discussed," Trump told reporters Friday.

Just months after the conclusion of special counsel investigation into Russian interference in the 2016 election, and the president's actions against that investigation, Murphy called the new details "pretty extraordinary."

"To ask a foreign leader to interfere in a presidential election -- right after a yearlong investigation into potential foreign interference in a presidential election -- would be pretty extraordinary. Even for these times," Murphy tweeted.