Moshe Katsav, the president, formally asked Ehud Olmert to form Israel's next government on Thursday.
"I have the honour to announce that I have decided to ask member of parliament Ehud Olmert to form the government," Katsav said at a ceremony with the Kadima party leader.
Olmert said he would quickly put together a coalition committed to carrying out his West Bank withdrawal plan and pledged that his government would set Israel's permanent borders within four years with or without Palestinian agreement.
"I hope to form a government, which will have the broadest possible support, as quickly as possible," Olmert, whose centrist Kadmina party won the most seats in Israel's election last week, said at a televised ceremony with Katsav.
"My political positions were expressed in detail and will also be expressed in detail in the written programme of the government that I will head."
Olmert said he would try to include a cross-section of parties from Israel's political spectrum in his government.
"It is not easy to form a coalition that is stable, that enjoys a secure majority that can last a full term"
acting prime minister of Israel
"It is not easy to form a coalition that is stable, that enjoys a secure majority that can last a full term," he said.
The centre-left Labour party, led by Amir Peretz, a former trade union leader, has already agreed to a political partnership with Kadima.
Kadima will now try to woo a number of smaller parties and set government guidelines.