Officials with Minnesota's largest public employee union say they have received several threatening phone calls and e-mails in response to their recent "tax the rich" ad campaign.

One voice message left at AFSCME Council 5 headquarters in South St. Paul prompted the union to file a complaint with police.

In the profanity-laced message, a man implied a connection to the tea party movement and a tea party event scheduled for Thursday evening outside of the State Capitol. He also said the union's days were numbered.

Executive Director Eliot Seide said the union will continue to push for tax fairness and will not be threatened.

"No mother or father in this state will tell their children to use language like this or speak like this. It's time to have a civilized dialogue," Seide said. "Civilized, intelligent people can agree to disagree, but this kind of thuggery doesn't deserve to be respected by any Minnesotan."

Union leaders say they were able to identify the caller as the owner and president of a legal printing firm in Minneapolis. They shared his name and phone number with reporters.

Attempts to contact the man were unsuccessful.