“The fact that it was allowed to persist at a critical agency that oversees the safety of our nation’s nuclear power plants is astonishing," McConnell said Tuesday. "The White House must now move swiftly with a replacement for Jaczko and I urge the Senate to move quickly to reconfirm the nomination of Kristine Svinicki as NRC commissioner before her term expires on June 30."

On Monday Jaczko announced his resignation from the NRC. Throughout his tenure, Jaczko has repeatedly clashed with the other members on the panel and faced allegations from his colleagues that he was seriously "damaging" aspects of the NRC — especially pertaining to health and safety.

While Republicans have strongly criticized Jaczko, they have also repeatedly urged Svinicki's confirmation. Some Democrats have voiced opposition to Svinicki, who is also a critic of Jaczko's tenure on the panel.. President Obama renominated Svinicki earlier in May.

"The only reason her nomination was held up by the White House and the Democrat-led Senate in the first place was because she had the courage to stand up to a hostile work environment, and to the bully who was responsible for it," McConnell said.