SALEM, Ore. (AP) — Former Gov. Barbara Roberts and other backers of Democratic Senate candidate Jeff Merkley, are criticizing Republican Sen. Gordon Smith for airing a “sleazy” TV ad featuring a rape victim accusing Merkley of failing to crack down on serious sex offenders.

“It’s a smear campaign ... and that’s what Gordon Smith continues to do,” Roberts said Monday at a news conference at Merkley’s campaign headquarters in Portland.

The rape victim, Tiffany Edens, stood by the ad and said she accepted Smith’s invitation to appear in it because she likes Smith’s voting record.

“I have made the choice and the decision to vote for somebody that will ensure the rights of victims. I have to stand by my convictions,” Edens said in an interview with KOIN-TV.

It’s the hardest hitting ad yet in what has become a knock-down brawl in Oregon’s U.S. Senate race. Smith is battling to hold onto his position as the only GOP senator on the West Coast in a race in which both sides have been blanketing the airwaves with attack ads.

In the rape victim ad, Edens asserts that Merkley, as Oregon House speaker, voted in the Legislature against extending the statute of limitations on rape. Edens has become well-known in Oregon for her fight to block serial rapist Richard Gillmore’s attempt to win parole.

Roberts and other Democrats called the TV ad a political smear, saying that the Smith camp cherry-picked one vote that Merkley cast during a 2005 fight with House Republicans to make him appear soft on crime.

The Democrats said Merkley has supported life sentences for repeat serious sex offenders, as well as an increase in the statute of limitations for sex crimes.

“I know Jeff and I know his record — he has always worked to protect all our families,” Roberts said. “In fact he supports tougher penalties for sex offenses. These ads are just lies.”

The new ad prompted Politico, a Washington, D.C.-based politics Web site, and others to observe that Smith appears to be trying to turn Gillmore into the “the Willie Horton of Oregon politics.”

That was a reference to the 1988 presidential campaign in which the first President Bush made Democrat Michael Dukakis the target of a hard-hitting ad about a furloughed rapist named Willie Horton.

Still, the Smith campaign and crime victims advocate Steve Doell on Monday scoffed at Merkley’s explanation for voting against the statute of limitations bill.

Merkley campaign spokesman Matt Canter has said Merkley voted against the bill cited by Smith as a symbolic protest against the “backroom deals” made by Republicans leaders in the closing days of the 2005 legislative session. He said Merkley supported a similar bill that would have increased time limits for bringing charges against people accused of violent crime.

Smith campaign spokeswoman Lindsay Gilbride said that in the case, Merkley put “partisan petty politics” above helping rape victims.

Doell, president of Crime Victims United, said Edens comes from a Democratic family, but agreed to appear in Smith’s ad because she believes Merkley hasn’t done enough to protect rape victims.

“This isn’t a partisan thing,” Doell said. “When somebody rapes you or assaults you, they don’t ask for your party registration.”