California's attorney general and election watchdogs are fighting back against a federal lawsuit seeking to bar disclosure of late donors to California's same-sex marriage ban.

Attorney General Jerry Brown, Secretary of State Debra Bowen and the Fair Political Practices Commission jointly filed arguments this week opposing the suit by the Proposition 8 campaign.

Ross Johnson, FPPC chairman, said Friday that the suit is "out to destroy campaign finance disclosure by a death-of-a-thousand cuts" and "I don't intend to let that happen on my watch."

U.S. District Judge Morrison C. England Jr. is set to hear oral arguments Thursday.

Absent a court order, the Proposition 8 campaign must disclose by Jan. 31 the names of donors from shortly before and after the Nov. 4 election. Previous contributors already have been identified.

California's Political Reform Act, approved by voters in 1974, requires disclosure of the name, occupation and employer of any individual who makes a campaign contribution of $100 or more.

Opponents of same-sex marriage are challenging the constitutionality of the disclosure requirement, claiming donors to Proposition 8 have been threatened after their names were revealed.

The suit cites numerous examples of threatening e-mails, phone calls and postcards - including death threats - allegedly made by opponents of the controversial ballot measure.

Ron Prentice, chairman of the Yes on 8 campaign, said recently that hundreds of people have alleged harassment, intimidation and threats occurring at their home or workplace.

Attorneys for the Proposition 8 campaign assert that First Amendment rights to be free from threats, harassment and reprisals outweigh the state's interest in compelling such disclosure.

Brown, Bowen and the FPPC counter that campaign disclosure assists the state in detecting efforts to hide the identities of large contributors and illegal spending of political funds for personal use.

"Political democracy demands open debate, including prompt disclosure of the identities of campaign donors," Brown said in a written statement.

"Backers of Proposition 8 should not be allowed to carve out a special privilege of anonymity for themselves," he said.

State officials argue that there is no compelling evidence that fear of reprisal inhibited donations to Proposition 8, which attracted 36,000 contributions totaling $30 million.

Attorney James Bopp Jr., representing the Proposition 8 campaign, said Friday that the state's argument misses the point because harassment occurred only after donors sent their money.

Bopp said the state has no compelling reason to disclose donations as low as $100.

"Surely, there's no one in the state who would be influenced to vote for or against an initiative because Joe Blow gave $100," he said. "That would be absurd."

Even without public disclosure, Bopp said, the state could audit campaign committees to obtain donors' names when investigating potential misspending or other illicit activity.

"They'd just have to keep the names confidential," he said.

The suit, if successful, would apply only to Yes on 8 committees, not to opponents of the measure or to other ballot issues.

Besides barring disclosure of late donors to the same-sex marriage ban, the suit would prohibit the public from continuing to view the personal information of donors previously identified.

Call Jim Sanders, Bee Capitol Bureau, (916) 326-5538.