A U.S. Supreme Court ruling Monday easing a key provision of a landmark campaign finance law could have a big impact on the 2008 presidential election.

The court ruled 5-4 to loosen restrictions on corporate- and union-funded television ads in the closing days of the primary and general elections, a decision that could give special interest groups more influence in the presidential race.

The high court's upholding of an appeals court ruling that a Wisconsin anti-abortion group should have been allowed to air ads in the final two months before the 2004 elections could also hurt the presidential aspirations of the law's co-sponsor, GOP Sen. John McCain of Arizona.

"Fair or unfair on McCain, it seems to be one more issue where he's ending up on the short end of the stick," said Kirk Jowers, director of the University of Utah's Hinckley Institute of Politics and a supporter of another Republican presidential candidate, Mitt Romney.

Jowers, a founder of Campaign Legal Center based out of Washington, D.C., that filed a brief with the Supreme Court backing the law commonly referred to as McCain-Feingold, said the decision will result in more negative advertising in the 2008 campaign.

"You will see a lot more ads that will attack candidates through legislative and policy positions in an attempt to fit within the standard established by the Supreme Court," Jowers said.

Randy Dryer, a Salt Lake City attorney who wrote a brief supporting McCain-Feingold for the Campaign Legal Center in an earlier case, agreed.

"I think we're going to see a resurgence of attack ads," Dryer said. "They'll again be challenged, but by the time they wind their way through the court system, the election will be long gone and determined."

The case involved ads that Wisconsin Right to Life was prevented from broadcasting, urging voters to contact the state's two senators, Democrats Russ Feingold and Herb Kohl, and tell them not to filibuster President Bush's judicial nominees.

Feingold, the other co-sponsor of McCain-Feingold, was up for re-election in 2004.

The provision in question was aimed at preventing the airing of issue ads that cast candidate in positive or negative lights while stopping short of explicitly calling for their election or defeat. Sponsors of such advertising contend they are exempt from federal contribution limits.

McCain downplayed the decision in a statement, calling it "regrettable that a split Supreme Court has carved out a narrow exception by which some corporate and labor expenditures can be used to target a federal candidate in the days and weeks before an election."

The Arizona senator pointed out the decision Monday has no effect on a more far-reaching component of the campaign finance law, a ban on the ability of political parties to raise unlimited and unrestricted amounts of money from unions, corporations and donors.