Ankeny, Iowa — Former Vice President Mike Pence opened his bid for the Republican nomination for president Wednesday with a firm denunciation of former President Donald Trump, accusing his two-time running mate of abandoning conservative principles and being guilty of dereliction of duty on Jan. 6, 2021.

On that perilous day, Pence said, as Trump supporters stormed the U.S. Capitol after the president falsely insisted his vice president could overturn the election results, Trump “demanded I choose between him and our Constitution. Now voters will be faced with the same choice.”

Pence is the first vice president in modern history to challenge the president under whom he served. While he spent much of his speech, delivered at a community college in a suburb of Des Moines, criticizing Democratic President Joe Biden and the direction he has taken the country, he also addressed Jan. 6 head-on, saying Trump had disqualified himself when he declared falsely that Pence had the power to keep him in office.

Trump’s statements about mass voting fraud led a mob of his supporters to storm the U.S. Capitol, sending Pence and his family scrambling for safety as some in the crowd chanted, “Hang Mike Pence!”

“I believe anyone that puts themselves over the Constitution should never be president of the United States, and anyone who asks someone else to put them over the Constitution should never be president of the United Sates again,” the former vice president said.