BURLINGTON, Vt. (AP) Lawyers for groups ranging from the American Civil Liberties Union, the Vermont Right-to-Life Committee, Rural Vermont and the National Voting Rights Institute squared off in U.S. District Court, as a legal challenge to Vermont's tough new campaign financing law has gotten under way.

The law, which went into effect in January 1998, places limits on campaign contributions and spending for statewide and legislative candidates. The law offers public financing to candidates for governor and lieutenant governor. The law also targets so-called soft money, by limiting indirect contributions and out-of-state contributions to 25 percent of a candidate's total campaign budget.

Vermont's law ''goes a long way toward protecting the integrity of the electoral process, as well as restoring public confidence in the election system,'' John Bonifiaz, executive director of the National Voting Rights Institute, said after Monday's testimony. The Boston-based public interest law firm is representing more than a dozen organizations and past and present political candidates in the suit.

The Right-to-Life Committee was the first organization to sue the state just days after the new rules were signed into law. Since then, the Vermont ACLU and the Vermont Republican Party have also joined the suit, charging the law unconstitutionally restricts candidates' and a donors' rights to free speech.

Under questioning from Mark Lopez of the ACLU, Mark Snelling said Vermont's law favors the incumbent candidate, who typically already has name-recognition among voters and a campaign organization.

''The law sentences a great number of potential candidates, in essence, to unsuccessful campaigns,'' said Snelling, who is son of and adviser to the campaigns of the late former Gov. Richard Snelling and former Lt. Gov. Barbara Snelling. ''It will be virtually impossible to compete with incumbents to effectively get a message across'' to voters.

Under questioning from Assistant Attorney General Eve Jacobs-Carnahan, Snelling said that political parties would be forced to expand the pool of donors they draw on in financing political campaigns.

For that reason, the law actually makes campaigns more expensive, said Darcy Johnston, a political consultant who has worked with Republican James Jeffords' past bids for U.S. Senate. Johnston testified that candidates must spend more money in attracting new donors, who are limited to a maximum contribution of $400 to a candidate in a statewide office in a two-year election cycle.

State GOP chairman Patrick Garahan testified that the law was too broad, and even contradictory, in its interpretation of a ''single source'' for political donations. Not only would the state Republican Party be forced to reorganize under the law, he said, but in doing so, the party would then be in violation of the existing laws governing organization of political parties.

Supporters of the law said they actually welcome the court challenge. The strategy, they said, is that ultimately, as one or the other side appeals the federal court decision, the U.S. Supreme Court will hear the case, and revisit the campaign finance issue.

It was the court's 1976 Buckley vs. Valeo ruling, which struck down many states' restrictions on campaign spending as unconstitutional.

At least three of the declared candidates for governor incumbent Democrat Howard Dean, Republican William Meub and Progressive Anthony Pollina have said they will accept the new law's public financing, which sets a $300,000 spending cap for challengers and $255,000 for an incumbent. Republican Ruth Dwyer said she will not accept public financing.

Nearly two dozen witnesses, including politicians, economists and campaign strategists, will testify in the trial, which is expected to last at least through May 19.