In Washington, White House spokesman Jay Carney called the election “another milestone in Georgia’s democratic development.”
Mr. Ivanishvili’s Georgian Dream party is described as fragile and could fracture easily. His hold on power also is threatened by Georgia’s complicated politics.
However, Mr. Saakashvili will retain his presidency until the end of his term in October 2013. The newly elected parliament is expected to nominate Mr. Ivanishvili as prime minister, but Mr. Saakashvili has to approve the nomination.
As he conceded defeat Tuesday, Mr. Saakashvili promised to remain a political force.
“We will struggle for the future of our country. We will struggle for everything that has been created in recent years in terms of a struggle against corruption, crime [and] in terms of Georgia’s modernization,” he said.
Few outside of Georgia had heard of Mr. Ivanishvili until he announced his entry into politics last fall. With an estimated fortune of $6.4 billion, Mr. Ivanishvili is Georgia’s richest man. The tycoon, who was raised on a farm, made his fortune in computers, banking and other investments in post-Soviet Russia.
Since returning from Russia eight years ago, he personally invested in Georgia’s infrastructure and personally financed many of Mr. Saakashvili’s reforms, paying the salaries of civil servants and police to help stamp out corruption.
Mr. Ivanishvili lives in a $50 million steel-and-glass mansion that overlooks Tbilisi and is known as an avid collector of art and rare animals.