Campaign finance reform and outside spending have emerged as contentious issues in the west metro's Third Congressional District, where DFLer Dean Phillips is challenging U.S. Rep. Erik Paulsen.

Phillips made campaign finance reform the focus of a Monday public forum in Edina with Tiffany Muller, president of End Citizens United, a national political action committee (PAC) that's targeting Paulsen and 19 other Republicans in Congress.

"We have to get our system back to you," Muller said. Phillips is "people-powered, not special interests-powered."

Citizens United vs. FEC is a 2010 U.S. Supreme Court decision that forbid restrictions on campaign spending by outside groups. End Citizens United, which began in 2015, is also targeting U.S. Rep. Jason Lewis this year.

Paulsen's campaign said Monday that, while Phillips speaks out about PAC money, he's silent about PAC money spent on his behalf, citing that End Citizens United PAC has reserved more than $500,000 on TV ads for Phillips. "Dean Phillips is a campaign finance fraud who wants to put our economy at risk by raising taxes and implementing massive new spending schemes," campaign manager John-Paul Yates said in a statement.

The battle for the Third District is shaping up to be one of the nation's most competitive House races. It is one of Minnesota's most expensive fights, as Phillips, a businessman and first-time political candidate, tries to unseat Paulsen, who has won re-election by wide margins since taking office in 2009.

It's also attracting a lot of national attention. In July, House Speaker Paul Ryan supported Paulsen at a Richfield event. And Monday, Phillips' forum, the first of four policy forums he's holding, included U.S. Rep. John Sarbanes from Maryland, who is chairman of the Democracy Reform Task Force, and former state Rep. Ryan Winkler. They took questions from the audience of about 100 people on issues ranging from lobbyists to campaign finance disclosure.

"We have a culture of corruption in Washington that is staggering," Phillips said.

Muller said Phillips is a "top priority candidate" for End Citizens United.

Last month, Phillips announced he raised $2.2 million mostly from individuals while Paulsen had raised $3.7 million over 18 months, with just over half of Paulsen's contributions from PACs. Phillips' top donors were individuals who work for Heartland Realty Investors, investment bank Houlihan Lokey, law firm Robins Kaplan and UnitedHealth Group.