The Democrat campaigns have already begun
A key element of the campaign finance reform act, which aimed to limit the influence of money on US politics, has been ruled unconstitutional by the courts.
The US court of appeals has said that two key requirements of the new law, which was expected to effect the 2004 presidential election, violate the free speech provisions of the US constitution.
By a split 2-1 judgement, it has repealed the act's ban on so-called "soft money" contributions by large companies and trade unions to political parties.
And it has also rejected the ban on special interest groups from political advertising in the 60 days before any federal election.
Such "attack ads" have often targeted political candidates for their stand on such issues as abortion or gun control.
If upheld by the Supreme Court, the decisions will fundamentally change the character of the 2004 election, where President Bush is already expected to have a huge advantage in fund-raising.
The court decision is a setback for Senator John McCain, the maverick Republican who stood against George Bush in the 2000 primaries, and long argued against the corrupting influence of money on US politics.
Under the McCain-Feingold Act, which took effect in November 2002, the presidential campaigns were supposed to be financed from individual donations which were limited to $2,000 per person.
It is a victory for the Republican National Committee, which objected to the ban on soft money, and the business group the US Chamber of Commerce, which said its free-speech rights were damaged by the ban on issue ads.
In the long lead-up to the US presidential election, millions of dollars have already been raised by Democratic hopefuls under the new rules.
The ruling came from a special three-member, fast-track panel made up of the US Appeals Court Judge Karen Henderson, District Judge Colleen Kollar-Kotelly and District Judge Richard Leon.
The lower court had been deadlocked on the decision since January.
Now, under a special provision, the case will go directly to the US Supreme Court for appeal.
The Supreme Court has formally finished hearing oral arguments this session, although it is still meeting under the end of June to deliver judgements.
But in light of the importance of the case for the next election, it could elect to hear the case this term.
It will, however, plunge the Supreme Court into the middle of political controversy just two years after it ruled by a split majority in Bush v. Gore that Mr Bush had been elected President after the Florida poll was disputed in the courts.