Rudy Giuliani, the personal lawyer to US President Donald Trump, has left two unintended voicemail messages on a reporter's phone, NBC News reports.
In the calls, Mr Giuliani reportedly spoke about needing money and attacked Democratic presidential candidate Joe Biden.
Mr Giuliani has not yet commented on the calls.
Lawmakers demanded document from Mr Giulliani earlier this month as part of the presidential impeachment inquiry.
In the past, he publicly admitted asking Ukrainian officials to investigate widely debunked corruption allegations against Mr Biden.
Three Democratic-led committees are currently investigating whether President Trump tried to pressure Ukraine's president into investigating Mr Biden in exchange for military aid.
What did Giuliani say?
NBC investigative reporter Rich Shapiro say he received two voicemails Giulliani in the space of a month.
He described them as the result of "what is known, in casual parlance, as a butt dial".
Mr Shapiro missed the first call, mid-afternoon on 28 September, because he was at a child's birthday party. He had interviewed Mr Giuliani for an article the day before.
For the entirety of the ensuing three-minute voicemail, the president's personal lawyer reportedly attacked Mr Biden and his family.
"Biden has been been trading in on his public office since he was a senator," Mr Giuliani reportedly said to an unidentified man. In the conversation, he brought up the discredited allegations that Joe Biden, when vice-president, stopped an investigation in Ukraine to protect his son Hunter.
"He did the same thing in China. And he tried to do it in Kazakhstan and in Russia," Mr Giuliani reportedly added.
In the second voicemail, left on the night of 16 October, Mr Giuliani again recorded a conversation with an unknown man.
"We need a few hundred thousand," Mr Giuliani reportedly said at one point, in a conversation that Mr Shapiro says covered Bahrain and an unknown man named Robert.
