Minnesota’s 8th Congressional District race between incumbent Republican U.S. Rep. Chip Cravaack and Democrat Rick Nolan is No. 6 on a list of races ranked by spending by outside groups — nearing $5.6 million as of Monday, the Duluth News Tribune reports.

(The site opensecrets.org, which tracks money in politics, ranked it as the No. 9 House race for outside money.)

The two had a lively debate this week, sparring over the economy and health care. The district, with a long history of left-leaning unions and right-leaning social conservatives, is traditionally a Democratic stronghold. But first-term member Cravaack surprised observers by beating longtime Rep. Jim Oberstar, D-Minn., two years ago.

A KSTP/SurveyUSA poll from earlier this month gave Nolan a 1-point lead, with 9 percent reporting that they are undecided: