The American Civil Liberties Union is expected to file suit Thursday, accusing California Secretary of State Bill Jones of creating a climate of fear to inhibit free speech by accusing Web sites that promote interstate "vote swapping" of criminal activity that "corrupts the election process."

The vote-swapping phenomenon - matching supporters of presidential candidates Ralph Nader and Al Gore in an alliance to advance both candidates' causes - continues to flourish nationwide and on at least one California-based site. Earlier this week, Jones' threats of legal action prompted Voteswap2000.com to shut its operations, and another site, Votexchange2000.com, warily did likewise. The ACLU is planning to sue Jones on behalf of the latter, sources within the organization say.

In a press release Thursday, the ACLU affiliates of Southern California and San Diego said they would seek a temporary restraining order against Jones, arguing that his threatened criminal prosecution against Voteswap 2000 not only prompted its shutdown, but created fears that led two other sites -- including the ACLU's plaintiff, votexchange2000.com -- to halt operations. The ACLU says it is also filing the lawsuit on behalf of a prospective voter. The National Voting Rights Project has joined the ACLU as co-counsel in the case.

"Votexchange2000 and other similar Web sites have a clear political message," said Peter Eliasberg, ACLU staff attorney at the ACLU of Southern California, "and that qualifies them for the highest level of protection under the First Amendment, whether or not Secretary Jones approves of their message or aim.

"The site expresses an unmistakable political message by their users seeking to associate with one another," Eliasberg continued. "This election year, perhaps more than any before it, every individual vote is crucial to both the election of a major party candidate and the building of a viable third party."

Another California-based site, VoteExchange.com, has continued to operate, its creators saying they are confident they are within the law. VoteExchange was created by two 24-year-old residents in Irvine, Calif., - software engineer Vinh Pham and graphic designer Joe Chang - and has reported more than 1,400 registrants since it the site went up over the weekend.

Pham is confident the site violates no laws, although its function is similar to the defunct Voteswap2000, which matched Nader voters in swing states such as Michigan or Oregon with Gore supporters in Republican strongholds such as Texas. The strategy is intended to help Gore win the electoral college, defeat Republican nominee George W. Bush and help Nader's Green Party reach its goal of 5 percent of the popular vote, thus qualifying the party for federal matching campaign funds in 2004.

Jones' accusations that Voteswap2000 amounted to a "conspiracy" and "a corruption of the voting process" in violation of California law has puzzled some legal observers. American University law professor Jamin Raskin, whose authorship of a Slate commentary Oct. 24 popularized the vote-trading idea, has suggested that Jones' actions are motivated more by allegiance to the GOP than First Amendment rights to free political expression, a charge Jones' office vehemently denies.

In a letter to Voteswap2000's creators, Jones wrote "any person or entity that tries to exchange votes or broker the exchanges of votes will be pursued with utmost vigor."

William Wood, chief counsel in the California Secretary of State's office, said authorities acted because VoteSwap2000 represented an obvious opportunity for voter fraud. Wood said he has studied another popular vote-swap site, WinWinCampaign.org, and concluded that it operated within California law because it functions more as a "discussion group" that does not actually broker vote exchanges.

While the ACLU was taking action in California, Oregon Secretary of State Bill Bradbury, a Democrat, joined in the crackdown, sending desist letters Thursday to six vote-trading sites, all of which are based outside the state. The fact that Bradbury is a Democrat and also co-chair of the Gore campaign in Oregon may deflect charges that Jones' actions sprang from partisan motivation. The swap activists, however, said that both major parties have a vested interest in fending off third party movements and protecting the status quo.

The exchanges, Wood said, apparently do not violate any federal law, but California, Minnesota and Wisconsin election officials already have instructed certain Web exchanges to cease operations. California law is so broad and strict, Wood said, that even married couples are prohibited from entering into such voting pacts. American University law professor Jamin Raskin, who popularized vote swapping in a commentary that appeared in Slate, says he is trying to determine whether California's law is unconstitutional or Jones' interpretation of it is.

Despite Jones anti-swapping vigor, hundreds of thousands of visits have been reported on such sites as NaderTrader.org, WinWinCampaign.org and VoteExchange.org. (There have been three variations on the phrase "vote exchange.") Many of the sites link to one another. While it is impossible to quantify how many swaps the sites have inspired, there are indications that it numbers in the thousands.

Sponsors of the sites say they have no profit motive in their efforts and are operating independently of the Democratic and Green parties. Pham says he is wary that the sites are vulnerable to trickery from Bush supporters passing as Nader fans to dilute Gore's support.

Despite Jones' strict legal interpretation, Californians are still being drawn to the vote-swapping strategy, site sponsors say, and so is at least one California Web firm. Tensa, an advocacy tools design firm in San Francisco, collaborated with Philadelphia-based Liberty Concepts in crafting WinWinCampaign.org for a Rhode Island client.

Californians, however, are being programmed out of another new vote-trading site called PresidentGore.com that went up Wednesday. Florida Web entrepreneur Scott Pitchford says he had registered the domain name two years ago without knowing how he would use it. He designed it to exclude Californians because he is uncertain of Jones' legal reach. "I just don't want the battle," Pitchford says.