Former Vice President Joe Biden’s campaign hit back at the GOP-led investigation into his son Hunter Biden’s dealings with Ukrainian energy company Burisma Holdings.

After the Senate Homeland Security Committee voted along party lines on Wednesday to authorize a subpoena against Democratic public relations firm Blue Star Strategies, which represented Burisma, the Biden campaign called the inquiry an attempt to reignite a “smear” and accused Sen. Ron Johnson, who chairs the committee, of trying to provide cover for President Trump’s response to the coronavirus pandemic.