Colombia's Constitutional Court has cleared the way for President Alvaro Uribe to stand for re-election in 2006.
Mr Uribe's hardline stance on security has won him support
Last month, the court ruled that presidents could seek a second term, but there was concern about their abuse of the office when campaigning.
The court has now endorsed rules for incumbents seeking re-election, which say the president is the only member of government who can actively campaign.
Opinion polls make the conservative Mr Uribe a clear favourite.
He says he needs four more years in office to implement his tough policies against armed groups and drug-traffickers.
Fears of violence
The court decided that a law which set out rules for sitting presidents running for re-election was constitutional, the court's chief said.
Mr Uribe had argued for a change in the re-election law, but opponents said that allowing re-election would give presidents too much power.
Correspondents say there are fears that left-wing guerrillas, who are desperate to avert another four years of Mr Uribe, will escalate a campaign of violence.
Mr Uribe is one of Washington's strongest allies in South America, where many governments have recently shifted to the left.