Sen. Joni Ernst (R-IA) is warning that former Vice President Joe Biden could face impeachment over his son’s dealings in Ukraine if elected in 2020.

Ernst, a first term lawmaker who sits on the Senate Judiciary Committee, told Bloomberg News on Sunday that the “door” for impeachment has been “opened.” In particular, the Iowa lawmaker cited Biden’s role in overseeing Obama administration policy toward Ukraine, while his son, Hunter, was simultaneously serving on the board of directors of one of the country’s largest natural gas conglomerates. Ernst said:

Joe Biden should be very careful what he’s asking for because, you know, we can have a situation where, if it should ever be President Biden, that immediately, people – right the day after he would be elected – would be saying, ‘Well, we’re going to impeach him,'” Ernst said.

The controversy surrounding Hunter Biden’s wheeling and dealing in Ukraine is at the center of President Donald Trump’s impeachment trial. Congressional Democrats claim that the president committed a crime when he suggested Ukraine look into how Hunter Biden secured his position with Burisma. Trump’s allies have countered that Hunter Biden’s role with the company was rife with potential conflicts of interests for his father.

The younger Biden joined Burisma’s board of directors in May 2014, around the same time his father was tapped as the Obama administration’s point man on Ukraine in response to Russia’s invasion of Crimea. Despite having no background in either eastern Europe or the energy industry, Hunter was paid as much $83,000-per-month for his services.

As Peter Schweizer detailed in Secret Empires: How the American Political Class Hides Corruption and Enriches Family and Friends, Hunter Biden’s background in banking, lobbying, and hedge fund management paled in comparison to that of current and past members of Burisma’s board.

Adding to concerns was that he joined the company at a time when it was actively courting western leaders to prevent scrutiny of its business practices. The same month of the appointment, Mykola Zlochevsky, Burisma’s founder, had his assets frozen in the United Kingdom on suspicion of money laundering.

A Ukrainian official with ties to Zlochevsky admitted in October 2019 the only reason Hunter Biden was tapped to join with Burisma was to “protect” the company from foreign scrutiny.

It is in the context of Burisma and Zlochevsky’s legal troubles that Joe Biden’s influence has raised the most red flags. The former vice president has particularly drawn questions over his conduct in demanding the Ukrainian government fire its top prosecutor, Viktor Shokin, in 2016.

Joe Biden, who has publicly bragged about the firing, reportedly threatened to withhold more than $1 billion in U.S. aid if the Ukrainian government did not remove Shokin. He has claimed the demand came from then-President Barack Obama, who had allegedly lost faith in the prosecutor’s ability to tackle corruption.

Unofficially, though, it was known that Shokin was investigating both Burisma and Zlochevsky for public corruption. It is uncertain if the probe extended to Hunter Biden, although Shokin has recently admitted that prior to his ouster, he was warned to back off the matter. Regardless of what occurred, Shokin’s successor, who is now himself being investigated for public corruption, dropped the investigation into Burisma.

After the investigation into Burisma was closed, Hunter Biden remained on Burisma’s board until his term expired in April 2019. During his tenure, Burisma wired millions of dollars to a Morgan Stanley bank account controlled by the younger Biden and his business associates. Between November 2014 and November 2015 alone, Burisma transferred more than $3.5 million to the account.

Given the history, Ernst believes there is enough evidence to warrant impeachment proceedings were the former vice president to be elected.

The Iowa Republican told lawmakers the reasoning had to deal with Joe Biden “being assigned to take on Ukrainian corruption yet turning a blind eye to Burisma because his son was on the board making over a million dollars a year.”