Talk about playing rough: Rep. Denny Smith (R-Ore.) has put Adolf Hitler in a campaign radio ad that attacks his Democratic challenger, Mike Ko- petski.

Kopetski, who came within 707 votes of defeating Smith in the 1988 election, told supporters shortly after the Iraqi invasion of Kuwait, "We shouldn't take military action. What we should do, though, is go through the United Nations." He said he hoped Iraq's aggression "isn't going to go any further than Kuwait."

A reporter attending the event published some of Ko- petski's remarks, and the verbal fireworks have not stopped.

Smith issued a statement accusing Kopetski of a "soft-headed policy of appeasement."

Kopetski replied by saying he was the victim of "a political smear." He claimed his remarks were taken out of context.

But Smith pressed on. At a news conference in front of a National Guard helicopter, he said Kopetski was "cozying up to Saddam Hussein."

Then, the radio ad began airing last week. It opens with a crowd roaring and the voice of Hitler is heard. The announcer follows:

"History teaches us that if you don't stand up to bullies and dictators, innocent people suffer. That's why the world has applauded America's measured and decisive action against Iraq's dictator, Saddam Hussein.

"Here at home, virtually every politician, regardless of party, is supporting our president . . . except Mike Kopetski. . . . Mike, appeasement is wrong."

At a news conference in front of Smith's Salem, Ore., headquarters late last week, Ko- petski called for an end to the negative tactics.