The move puts pressure on other GOP candidates to do the same.
Priorities USA Action, the Democratic super PAC poised to serve as Clinton's top advertising ally, pulled in $15.6 million, including $2 million from Haim Saban.
Clinton's forceful foray into race relations comes three days after nine African Americans were gunned down at a Charleston, S.C., church.
Speaking to fundraisers in Brooklyn, Clinton also reiterated her support for a constitutional amendment that would overturn the decision.
Clinton Foundation to restrict foreign donations, adopt new enhanced disclosure policy
Organizers argue that they've succeeded at their goal: Proving that Clinton has the support to win the presidency.
Hillary Clinton said Tuesday the GOP Iran letter challenged President Obama's status as commander-in-chief.
He plans to exit the White House next month.