Alexander Rondeli, a Georgian political analyst, said the antagonism between Saakashvili and his future prime minister threatened to create a political storm.
"Both the president and Ivanishvili have stated, not very willingly, but they have stated their readiness to work together," Rondeli said. "But on Ivanishvili's team are people who, metaphorically speaking, want Saakashvili's head. Whether he will be able to resist their influence only time will tell."
Saakashvili was under pressure to hold a democratic election and prevent the kinds of violations believed to have boosted his results in the past. This message was reinforced by U.S. Secretary of State Hillary Rodham Clinton during a visit in June, when she told him that the "the single best thing Georgia can do to advance your security, your prosperity, your democracy, your international reputation, is to hold free and fair elections that result in a fully democratic transition."
More than 400 international observers monitored the election. They expressed concern over the harsh rhetoric during the campaign and isolated cases of violence, but said Tuesday the election process had showed "a healthy respect for fundamental freedoms at the heart of democratic elections."
Ivanishvili has confirmed his commitment to pursue Saakashvili's goals of making Georgia an integral part of Europe and member of NATO, while adding he will seek to restore the trade and diplomatic ties with Russia that were severed after the 2008 war.
Georgian producers of wine, mineral water, vegetables and fruits had depended on exports to Russia, and the closing of those markets hurt them deeply.
The businessman has denied Saakashvili's accusations that he intends to put Georgia back under Russian domination.
Before Saakashvili conceded, Ivanishvili met with two U.S. senators to assure them of his desire to maintain the close relationship with Washington that Saakashvili forged.
"We talked about the future, how to develop our relationship with our big friend (the United States), and how to develop democracy in Georgia," he said after meeting with Republican Sen. James Risch of Idaho and Democratic Sen. Jeanne Shaheen of New Hampshire, both members of the Foreign Relations Committee.
In Moscow, Russian Prime Minister Dmitry Medvedev said the opposition victory would bring "more constructive and responsible" people to parliament. He said the Kremlin political party was "ready for dialogue about the future of Russian-Georgian relations."
Alexei Malashenko, a scholar at the Carnegie Moscow Center, was more cautious.
"For a while, ties will soften, there will be a prospect of improvement, but an exchange of embassies is not possible yet," he said.
One of the main obstacles is the status of the breakaway Georgian provinces of South Ossetia and Abkhazia, which Russia has recognized as independent. Georgia lost its last remaining territory in both provinces as a result of the 2008 war and bristles at the Russian troops stationed there.
Misha Dzhinzhikhashvili in Tbilisi and Mansur Mirovalev in Moscow contributed reporting.
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