When Amy Klobuchar hit the major themes of her Senate campaign in this Mississippi River town — bungling in Iraq, the need for change in Washington — the Democrats on hand applauded politely.

What excited the crowd was her tough talk about countering Republican attacks.

"They are smearing us. They are swift-boating us," Klobuchar told about 50 supporters at a riverside park. "I predicted it in June. It's their strategy, and we won't let them get away with it."

A month before the election, Klobuchar shows no sign of sitting placidly on her lead over Republican Rep. Mark Kennedy. After he launched a TV commercial criticizing her record as county prosecutor, she struck back with an ad featuring crime victims praising her performance and noting her endorsement by the state's largest police organization.

Democrats are thrilled.

"When I was running for chairman last year, it was the main thing I heard — we need to define ourselves and not let the Republicans define us instead," said Brian Melendez, chairman of the state Democratic Party.

Many Democrats think the party didn't do enough in 2002 and 2004 to counter negative perceptions created by Republican advertising, particularly the 2004 attacks on party presidential nominee John Kerry by Swift Boat Veterans for Truth. That campaign turned what was supposed to be Kerry's strength, his service in Vietnam, into a weakness.

"They sat back and waited to respond, and by the time they did it was too late," Klobuchar said in an interview. "I don't believe you sit back on your heels when someone is attacking you."

Klobuchar's two terms as Hennepin County's chief prosecutor are her chief asset, giving her a tough-on-crime image that has eluded many Democrats. But Republicans see a vulnerability after a recent spike in violent crime in Minneapolis, the county seat, and have tried to turn the tables on her.

"She says she's a prosecutor, and she says she's tough on crime, but we have numerous examples where she's not done the things she said she'd do," said Heidi Frederickson, spokeswoman for the Kennedy campaign. "And it's had severe consequences for the people of Hennepin County."

Kennedy's ad follows that line, contending that Klobuchar broke promises she made to crack down on drug dealers and armed criminals.

The Klobuchar ad hits back with testimonials, including one from Linda Longino, the mother of an 11-year-old murder victim named Tyesha Edwards.

"When our little girl Tyesha was murdered, Amy saw to it that those gang members were put away," Longino said. She closes the ad by stating: "Mark Kennedy, you should be ashamed."

Melendez said Democrats he talks to love the Klobuchar ad. "I'm hearing extraordinarily strong responses," he said.

Klobuchar, 46, said she'll continue to respond aggressively to anything she considers negative advertising. Independent polls have showed her with a double-digit lead over Kennedy.

Klobuchar's only major misstep came last month, when her chief spokeswoman watched an unreleased Kennedy TV ad that had been obtained, perhaps illegally, by a liberal blogger. Klobuchar fired the spokeswoman and turned the matter over to the FBI, and there's been little indication it will cost many votes.

"I found it kind of confusing," said Joyce Fiedler, a moderate Democrat from suburban Minneapolis who said the incident wouldn't keep her from backing Klobuchar. "But it seems pretty clear she took decisive action and didn't tap-dance around it."

For Kennedy, it's his toughest fight yet in a career marked by winning a series of tough elections.

Six months ago, Republicans viewed the race as their top prospect for seizing a seat now held by a Democrat, retiring Sen. Mark Dayton. Klobuchar and Democrats have worked for months to portray Kennedy as aligned too closely with the Bush administration and top Republicans on most issues.

Kennedy, 49, has countered, citing his independence from the GOP on some issues. He has criticized the No Child Left Behind education law because of the loss of local control. He has expressed concern about the environment in opposing drilling in the Arctic National Wildlife Refuge.

Leading state Republicans acknowledge that Kennedy's campaign has so far failed to resonate with enough voters.

"He faces an uphill climb — there's no question about that," said Sen. Norm Coleman, an early supporter of Kennedy's candidacy. "He's the underdog right now. I think he would say the same."

Kennedy at the end of the last federal fundraising cycle still had nearly $500,000 more in the bank then Klobuchar, $3.4 million compared to $2.95 million. That guarantees he'll have the resources to go to the airwaves with criticisms of Klobuchar's record. Klobuchar, who outraised Kennedy in the last two reporting periods, is likely to be able to match him step for step.

During the summer, Klobuchar went on the air with several commercials touting her prosecutorial background, while Kennedy ran a series of quirky ads, many featuring his family, that attempted to leaven his dry reputation. That Kennedy ad and others turned off Sam Richter, a Republican-leaning independent from the suburbs.

Richter called the ads "goofy" and said he'd like to see Kennedy spell out where he stands on the issues.

"I don't care about the negative stuff they can dig up on Amy Klobuchar," Richter said. "If Mark Kennedy comes out and says, here are the things I've done and here are the reasons I think I'll be a good senator, here's where I stand — that's what I'm waiting to hear."