The highest court in Ukraine has approved a proposal for parliament to elect presidents, rather than directly.
Kuchma's allies have been facing a strong opposition challenge
The Constitutional Court move could be a blow to opposition parties hoping to replace the incumbent, Leonid Kuchma, at next year's presidential election.
The court ruling clears the way for Mr Kuchma's majority in parliament to vote the constitutional amendments through.
Economic woes and allegations of political violence have damaged Mr Kuchma's popularity in recent years.
Viktor Yushchenko, a former prime minister and now the leading opposition lawmaker, has been tipped to win the 2004 vote but the Constitutional Court's ruling is seen as a victory for Mr Kuchma's camp.
According to one of the amendments, the parliament, or Supreme Council, would elect a new president next year to serve until a fresh parliamentary election in 2007 - one year later than scheduled.
A spokeswoman for Mr Yushchenko condemned the ruling, saying that opinion polls showed than only 10% of Ukrainians were ready to allow parliament to choose their future presidents.
"The Constitutional Court issued its opinion but the people of Ukraine have their own opinion," said Irina Herashchenko.
The Constitutional Court also ruled that President Kuchma, whose time in office has been marred by scandal and allegations of corruption, will not face any criminal prosecutions while he is in power.
Mr Kuchma is only allowed to serve two terms as the country's leader but Thursday's rulings may mean that he will attempt to prolong his rule or at least ensure a successor takes the post and provides him with immunity from prosecution, the BBC's Helen Fawkes reports from Kiev.