ST. PAUL, Minn. (AP) — The nation’s most powerful gun rights group plans to spend close to $1 million in a weeklong, pre-Election Day ad blitz targeting Minnesota U.S. Rep. Rick Nolan.

The National Rifle Association’s massive ad buy — $750,000 over just one week starting Oct. 28, according to public filings — adds to the flood of outside money that has made the race for the 8th Congressional District the most expensive contest in Minnesota by far. NRA spokeswoman Jennifer Baker confirmed the ads would focus on the 8th District but declined to say whether they would criticize Nolan, boost his Republican challenger Stewart Mills or both.

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No matter the message, it could be potent in the 8th District, home to northeastern Minnesota counties with some of the highest gun permit ownership rates in Minnesota.

Guns have played heavily into the high pressure race, making appearances in nearly every ad, debate and interview the two candidates have done. Mills has tried to put Nolan on defense with gun owners, accusing the Democratic congressman of trying to strip gun owners of Second Amendment rights.

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Nolan has defended his support of an assault weapons ban, limits on magazine capacity and other proposals as common-sense regulation that don’t conflict with the hunting-friendly lifestyle of the 8th District. Nolan’s campaign did not immediately respond to a request for comment.

“There have always been restrictions on the Second Amendment,” Nolan previously told the Associated Press. “You can only have six shells in your shotgun when you’re shooting ducks. Why should you be able to have 100 in your rifle when you’re shooting people?”

Baker cited those votes and others in Nolan’s “F” grade with the NRA. The NRA announced its endorsement of Mills this week. Baker called Mills “the only person in the race who is committed to protecting our Second Amendment rights.”

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