Here are some of the top spenders on political advertising in Minnesota during four weeks in September and October, according to the Federal Elections Commission. Some spent on national races. The list doesn't reflect spending by groups that do not file forms with the FEC for various reasons.

1. U.S. Chamber of Commerce (business) $1.9 million

2. Alliance for a Better Minnesota (labor) $882,000

3. Patriot Majority Midwest (liberal advocacy) $624,000

4. Health Care for America Now $517,000

5. American Rights at Work (labor) $516,000

6. Americans for Job Security (business) $452,000

7. AARP (retired Americans) $426,000

8. American Medical Association $225,000