Former Rep. Richard Pombo (R-Calif.) and environmental groups are picking up their feud right where they left off in 2006.

Defenders of Wildlife’s advocacy arm, Defenders of Wildlife Action Fund, spent $64,000 in independent expenditures opposing Pombo in March, according to reports filed recently with the Federal Election Commission. The money went largely to two weeks of radio ad airtime in California’s 19th district, where Pombo is competing with two other Republicans for the party’s nomination.

In a March release, the group said the 60-second radio ad buy “represents only the beginning of Defenders Action Fund’s campaign to keep Pombo from returning to Congress.”

Pombo, who earned the enmity of environmental groups for his crusade against the Endangered Species Act while chairman of the then-House Resources Committee, is trying to turn the attacks to his advantage in an area where agricultural interests tend to overshadow environmental ones.

The former Congressman, who represented the neighboring 11th district, launched his own radio ad last week calling Defenders of Wildlife one of “the extreme environmental groups fighting to cut off water to our Central Valley farms.”

“I’m honored by every attack from radical environmentalists — because I’ll always fight against their liberal ideals which are decimating the Central Valley,” Pombo added in a release.

The back and forth is bound to get more intense as the state’s June 8 primary approaches. Given the district’s strong Republican lean, the winner of the GOP primary is likely to succeed retiring Rep. George Radanovich (R).