Campaign Money Watch is again hitting Republican U.S. Senate nominee Bob Schaffer over a 1999 investigative trip to the Northern Marianas Islands paid for by Jack Abramoff's lobbying firm.

The 527 group made a six-figure television ad buy on all Denver broadcast stations this week, the Colorado Independent reported.

The ad accuses then-Congressman Schaffer of taking "a luxury trip" to the Northern Marianas Islands paid for by Abramoff's firm Preston Gates in 1999. Abramoff was hired by the Islands' government to lobby against stricter labor laws there.  

"Schaffer claimed he was investigating," the ad states. "But when Schaffer returned, he defended the sweatshops. And he's taken thousands in contributions from the sweatshop owners."

Campaign Money Watch aired a similar television ad this summer asking whether Schaffer "look(ed) the other way" during an investigative trip to Northern Marianas sweatshops following reports that workers there were forced to have abortions.

Schaffer has repeatedly denied any wrongdoing and said he has never met Abramoff, who pleaded guilty to fraud, conspiracy to bribe, and other charges in 2006.

The issue was brought up early in the campaign when Schaffer told the Denver Post in April that the Northern Marianas' guest-worker program "works very well" and should be a "model" for a nationwide program.