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Just six days out from a closely contested Democratic Senate primary vote in Oregon, state House Speaker Jeff Merkley and attorney Steve Novick are taking different approaches with their advertising strategies. While Merkley is fighting back against negative ads from Republican incumbent Gordon Smith and going after Novick with an attack ad, Novick has pledged to stay positive for the remainder of the race.

In Merkley's first TV ad of the month, "Places" (subscription), he highlights his working-class background, claiming that "Gordon Smith and I come from two very different places." An announcer then outlines Merkley's plans to help working-class families who are feeling the pinch from a slow economy.

Merkley was also quick to respond to a negative ad (subscription) released on May 2 by Smith, firing back just two days later with "Kidding" (subscription), which accuses Smith of hypocrisy and of "falsely" attacking Merkley. "Gordon Smith. Who is he kidding?" an announcer asks. Responding to Smith's claim that Merkley violated fundraising rules, the announcer insists that "Merkley enacted the toughest ethics reforms in Oregon's history," whereas it's "Smith who's taken a quarter of a million dollars from Big Oil and voted to give them billions in special tax breaks." Seeking to counter Smith's claim that he is a candidate of change, the ad labels him "just another special-interest senator."

Shifting his attention back to the primary, Merkley targets his Democratic opponent in "Believe " (subscription), which accuses Novick of making insulting comments about fellow Democrats Hillary Rodham Clinton, Barack Obama and Oregon Rep. Darlene Hooley. "Jeff Merkley believes in bringing us together... That's the change Democrats need," an announcer concludes.

In a statement, Novick manager Jake Weigler called the ad "a pitiful reflection on how much their campaign is running on empty. No one has even brought up these comments or objected to them except for Jeff Merkley... The one dividing Democrats here is Jeff Merkley."

But rather than retaliate directly over the airwaves, Novick opted to use what the campaign says will be his last paid advertisement (subscription) before the primary to tout his support from former Oregon Gov. John Kitzhaber (D), who narrates the ad. A clip of Merkley's "Believe" appears on screen, and Kitzhaber asks: "Negative politics as usual? Or something different?" Sticking to Novick's theme of unconventionality, Kitzhaber says: "Steve Novick is not a typical politician, and he's not running a typical campaign." Quotes from newspaper endorsements flash on screen, as Kitzhaber pronounces Novick to be "the cure for politics as usual."

A recent poll (subscription) shows Novick with a slight advantage over Merkley, 29 percent to 23 percent, but that is barely outside of the survey's 5-point margin of error; more than four in 10 Oregon Democratic voters say they are still undecided.