Former Rep. Mark Sanford, R-S.C., said on Monday that he is curious to know about former Vice President Joe Biden’s son's business dealings in Ukraine.

“What’s going on there is the proverbial swamp,” Sanford told “America’s Newsroom.”

“It’s all that irks most normal people about what they don’t like about Washington D.C.," said Sanford, who has announced a 2020 presidential primary challenge to President Trump.

Former Prime Minister of Ukraine Mykola Azarov said last week that authorities must investigate Hunter Biden to establish whether or not his role on the board of a Ukrainian gas company complied with the nation’s laws.

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Azarov, who served under Ukraine's former pro-Russian President Viktor Yanukovych, did not specify to which laws he was referring. Trump and his personal attorney Rudy Giuliani have called on current Ukrainian President Volodymyr Zelensky to investigate the Biden family's dealings with Ukrainian firm Burisma Holdings.

Burisma reportedly paid Hunter up to $50,000 per month to sit on its board at the same time his father was leading the Obama administration's diplomatic dealings with Kiev. A second private equity firm founded by the younger Biden also reportedly received $3.4 million from the same company.

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Trump and Giuliani have alleged that when Ukrainian prosecutors tried to investigate Burisma Holdings for corruption, then-Vice President Biden pressured the government to fire the head prosecutor. Biden has denied knowing about his son's business dealings.

Sanford went on to say, “The fact that, you know, somebody’s son, daughter, relative, friend, ends up with a plum assignment or a plum-paying position just because of where Dad happens to be is everything that’s wrong with Washington, D.C.”

Sanford said Democrats' efforts to impeach Trump over the phone call to Zelensky are "going nowhere" in the Senate. He said the House should formally "censure" Trump, if wrongdoing occurred, and move on.

The Associated Press contributed to this report.