The 30-second spot features images of the collapsed bridge, littered with overturned cars.
"When the unthinkable happened, Sen. Norm Coleman teamed with Amy Klobuchar to secure $250 million to rebuild the 35W bridge," the ad says.
A group called American Future Fund is paying for the ad, which the Coleman campaign says it has nothing to do with. Minnesota Public Radio News was unable to reach the group.
The International Union of Operating Engineers, Local 49, said it wants the ad pulled immediately. One of the union's members was killed when the bridge collapsed. Twelve other people also died.
"It was really a tragic event for a lot of us, and we just don't like to see it used ... for political purposes."
Local 49's political director Adam Duininck said it's wrong to use the tragedy in a campaign ad.
"It doesn't sit real well with us because of how personal I think it is for some of our members, and some of the people that were working on that bridge," Duininck said. "It was really a tragic event for a lot of us, and we just don't like to see it used as an issue ad -- used for political purposes."
The union has endorsed DFLer Al Franken's campaign against Coleman.
Coleman's campaign said it will not demand that American Future Fund pull its ad.
"We have had nothing to do with these ads or their content," said Coleman campaign spokesman Tom Erickson. "There have been four different organizations that have spent hundreds of thousands of dollars running negative ads against Sen. Coleman. There was never any call for removal of these ads by Al Franken and his Democrat allies."
Carleton College political scientist Steven Schier said he's not surprised the bridge made its way into a campaign ad. And he doesn't think the commercial crosses a line.
"It just doesn't strike me as a terribly offensive ad," he said.
Schier said he wouldn't be surprised if the bridge is featured in future political advertising.
"The bridge is a -- how should we say it? A high-temperature symbol in state politics," Schier said. "So it's understandable that there's going to be partisan fighting about this. Basically, you can expect that when either side can find a reason to take offense at another one's ad they'll be issuing press releases like this. And I think we can just expect a steady cycle of this from now through November."
Schier said polls show Minnesotans have been generally happy with the response following the bridge collapse. He said the group backing Coleman is trying associate Coleman with those positive feelings.
The ad doesn't even mention that Coleman is a Republican, and instead labels him an independent voice for Minnesotans. Schier said that's no surprise either.
"The Republican brand this year is not very popular. People generically prefer Democrats to Republicans, so it's not a surprise to me that this ad wouldn't mention that Norm Coleman is a Republican," Schier said.
"Also, elections are won in the political center and the public is looking for more bipartisan cooperation," Schier continued, "and this ad tries to squarely put Norm Coleman in the political center as a leader in bipartisan cooperation."
A political newsletter says the ad will air for about three weeks in the Minneapolis and Mankato markets.