Ralph Nader can be listed on Florida ballots as a candidate in the US presidential election after a ruling by the state electoral chief.
Nader has already been struck off the ballot in four states
The decision contradicts a temporary court order which told Florida to keep Mr Nader off the ballot.
The Democratic party has reacted angrily, calling the move "blatant partisan manoeuvring".
It fears the decision could help President George Bush win the key swing state, where his brother is governor.
In a memo to Florida county election supervisors, Florida State Elections Director Dawn Roberts said Mr Nader's name should be included on ballot papers.
She said she had been forced to act ahead of a hearing on a permanent injunction on Wednesday because of potential disruption from Hurricane Ivan.
'Leg up for Bush'
The Democratic Party has challenged Mr Nader's appearance on the ballot as a Reform Party candidate on the grounds that the organisation does not qualify as a national party under state law.
"I'm in disbelief," said Florida Democratic party chairman Scott Maddox after news of Ms Roberts's decision.
"This is blatant political manoeuvring on the part of [Governor] Jeb Bush to give his brother a leg up on election day."
Governor Bush said he agreed with the latest decision.
"It's up to the judge to determine, based on the law, whether Nader should be on the ballot or not," he said.
The Reform Party has accused the Democrats of stifling democracy.
"Scott Maddox wants to decide whose votes get counted," party spokesman Patrick Slevin told the Miami Herald.
A legal battle has been raging over Mr Nader's candidacy in Florida.
Florida circuit judge Kevin Davey issued a temporary ban last week, siding with the Democratic challenge.
On Monday, Republican State Secretary Glenda Hood created confusion when she restored Mr Nader to the ballot by appealing against the temporary ban - a move which automatically lifts it.
Judge Davey is due to hear the case on Wednesday to decide on whether or not to impose a permanent injunction.
Many Democrats believe Nader cost Al Gore the presidency
The case is also due to be heard by the state Supreme Court, but only after Judge Davey has made his decision.
The confusion over the issue has caused havoc with deadlines for printing ballot papers for the election in November.
Overseas absentee ballots are due to be sent by the weekend.
A number of counties have decided to print two ballots - one with Mr Nader's name on it, and one without.
Mr Nader was a Green Party candidate in the 2000 US presidential election, when Mr Bush controversially won Florida and the presidency.
Analysts say most of the 98,000 votes Mr Nader won in Florida would have gone to the Democratic candidate Al Gore had Mr Nader not appeared on the ballot.
That would have changed the overall outcome of the election, they suggest, and put Mr Gore in the White House.