A union official's comment that Democratic Senate hopeful Robin Carnahan would beat the backside of opponent Roy Blunt has the Republican's campaign bemoaning the loss of civility in what already was framing up to be a no-holds barred race.

Blunt spokesman Rich Chrismer accused Carnahan's campaign of going "deeper into the gutter."

"Robin Carnahan's big labor union bosses are really raising the level of discourse," Chrismer said.

In introducing Carnahan at an AFL-CIO event Tuesday downtown, the union's state president, Hugh McVey, promised she would "kick Blunt's ass."

Carnahan, in her speech, was less profane, but just as emphatic, accusing Blunt of trying to "stick it to us."

The fiery union meeting came the same day that the Carnahan campaign unveiled a new ad targeting Blunt for attempting to insert legislation in a Homeland Security bill that would have benefited the tobacco firm Philip Morris . (The ad doesn't mention that Blunt would later marry a lobbyist for the company.)

Blunt's campaign will probably not take this latest salvo sitting down -- don't be surprised if it leads to a back-and-forth that could set the tone for the rest of the campaign.

In other words: If you thought a little butt kicking was out of bounds, just wait until November.