The event, organized by Indivisible Denver and its sister organizations, was billed as a casual gathering to get to know the candidates, rather than a debate.
Dunn previously worked under former Colorado Attorney General John Suthers. He must be confirmed by the Senate before assuming the role.
About 70 former U.S. attorneys, including John Walsh of Colorado, call the Trump policy "dangerous, expensive, and inconsistent with the values of the institution in which we served."
John Walsh pushed for justice department guidance on how to prosecute marijuana during his tenure, and says the Trump administration is making a mistake in reversing course.
Walsh participated in President Obama’s gathering this week on fighting extremism.