JERUSALEM — Foreign Minister Tzipi Livni, the head of the largest party in Israel’s parliament, called on opposition leaders to join her government after she was asked by President Peres to try to form a ruling coalition.

The 50-year-old politician is trying to become the first woman in more than three decades to become prime minister, at a time when the country faces both economic and political challenges.

“I accept the responsibility and I do not take it lightly,” Ms. Livni said at the ceremony, which was broadcast live on Israel’s Channel One. She later added that she aspired to forming a broad coalition that would include Prime Minister Netanyahu’s Likud and other parties.

Ms. Livni won a Kadima primary last week to succeed Prime Minister Olmert as party leader. Mr. Olmert, who took office after Ariel Sharon suffered a stroke and fell into a coma in January 2006, resigned two days ago in the face of police recommendations that he be indicted for bribery and other corruption charges. He denies wrongdoing and will remain as caretaker premier until a new government is formed.

The next prime minister will lead Israel while it pursues Middle East peace talks and contends with what it asserts is Iran’s attempt to develop nuclear weapons. The economy is facing its slowest growth in five years amid the global credit crisis.

“These are not normal days,” Ms. Livni said. “Israel faces many challenges — security, political, economic, and social challenges. Israel needs stability and a government that includes most of the parliament’s parties and represents most of the country’s people.”

Before naming Ms. Livni, Mr. Peres met with delegations from all 13 parties in parliament.

“In these meetings I came to recognize the desire of all of the factions to bring, as quickly as possible, stability and leadership, and to allow the government that will arise to confront the challenges that stand before the state,” he said.

If Ms. Livni doesn’t retain the support of the existing Cabinet or assemble a new coalition within 42 days of being nominated by Mr. Peres, then national elections could be held within months. Kadima commands 29 seats on its own, though it controls a bloc of 64 seats in the 120-member Knesset through its alliance with the Labor, Shas, and Pensioners parties.

Dan Schueftan, the deputy director of the National Security Studies Center at Haifa University, said he “would bet against” Ms. Livni being able to assemble a coalition.

[Also yesterday, a driver plowed a BMW into a group of soldiers at a busy intersection near Jerusalem’s Old City, injuring 13 of them before he was shot to death, Israeli police and the rescue service said according to the Associated Press.]