Montenegro's Prime Minister Milo Djukanovic, the longest-serving leader in the Balkans, has resigned.
"The conditions have been created for me to step down," he said, adding that he would stay "at the helm of the Democratic Party of Socialists".
This month Montenegro achieved candidate status in its bid to join the EU - a key step towards accession.
Mr Djukanovic, 48, spearheaded Montenegro's successful campaign for independence from Serbia in 2006.
Mr Djukanovic, who first served as prime minister in 1991 and was later president, told a news conference he was stepping down after serving in top posts for two decades, and not because he was being forced to.
"This decision of mine is not sudden or rash, and was not reached, as certain irresponsible individuals claim for reasons known only to themselves, under anyone's pressure, either from the inside or from the outside," he said.
He added: "Today, when Montenegro is a stable country, when it is out of the recession, when it has become a candidate for EU membership, when it is in Nato's front room... conditions have become ripe for my withdrawal from the executive authority."
He said the time was right for a change and that his party's leadership had already proposed Deputy Prime Minister and Finance Minister Igor Luksic to lead the new government.
"I want to ease back on the throttle in a more relaxing business environment," Mr Djukanovic said.
He once faced charges in Italy for allegedly being part of a Balkan cigarette smuggling ring in the 1990s, but said he was leaving office with a clean record.
"I can say that I am withdrawing from the executive authority with a clean conscience and head held high, pleased with what I and my team have done," he said.
In May 2006 some 55% of the population voted in a referendum to end Montenegro's union with Serbia, which had been created only three years earlier from the remnants of Yugoslavia.