Clinton, back in Iowa. (Michael B. Thomas/AFP/Getty Images)

MONTICELLO, Iowa -- Hillary Rodham Clinton is calling for changes to the nation's campaign finance system, saying here Tuesday that she would support a constitutional amendment if that's what it takes to fix what she called a "dysfunctional" system.

Holding her first official campaign event at Kirkwood Community College in rural Monticello, Clinton identified campaign finance reform as one of several pillars of her 2016 presidential campaign.

"We need to fix our dysfunctional political system and get unaccountable money out of it once and for all -- even if it takes a constitutional amendment," Clinton said in opening remarks at a roundtable event with Kirkwood students and instructors.

The 2016 presidential election is expected the be the most expensive in U.S. history, with super PACs and campaigns likely to spend billions of dollars.

Clinton's comments come as many of the Democratic Party's biggest donors, as well as her super PAC allies, are gathering in San Francisco for a meeting of the Democracy Alliance.