Israeli Prime Minister Ariel Sharon is widely expected to be re-elected for a second term in Tuesday's elections. Opinion polls give him a wide margin over his main challenger, Labor Party leader Amram Mitzna. But as Mr. Sharon's ruling Likud Party is likely to face a more difficult task in forming a stable coalition government.

Mr. Sharon's Likud Party is expected to become the biggest party in the Knesset, with surveys indicating the faction may win as many as 33-seats in the 120-member parliament.

By contrast the Labor Party led by Mr. Mitzna, a newcomer on the national political scene, is expected to win less than 20 seats.

But while there seems little doubt that Likud is likely to be a big winner, Mr. Sharon may not find it so easy to form a new government.

No party in Israel's history has ever won enough seats to rule on its own, and this election is likely to be no different. That means that Prime Minister Sharon, soon after the votes are counted, will probably have to begin the arduous process of forging agreements with other factions.

The task is likely to prove particularly difficult this time around, since the Labor Party, Likud's main partner in the last government, has already rejected the idea of serving again in a Likud-led cabinet.

Other parties likely to be considered as potential partners, include the secular-centrist Shinui faction, led by former journalist Tommy Lapid.

Shinui is expected to become a formidable force in the parliament, with opinion polls suggesting it will jump from six to 16 seats.

But Mr. Lapid's conditions for agreeing to serve in government may be too hard for Mr. Sharon to accept.

The leader of Shinnui says the party will not sit in a coalition that includes ultra-orthodox Jewish religious parties, including Shas, which is expected to win 13 seats.

Such obstacles will make it hard for Mr. Sharon to build a stable cabinet. Because of this, some observers are predicting that the next government will be unstable and unlikely to last for a full four-year term.

The elections are also taking place under the threat of more Palestinian terror attacks. About 26,000 security personnel have been deployed across the nation to protect the almost five million Israelis who are eligible to vote in Tuesday's poll.

In addition, Israel has imposed a ban, which will remain in force until Wednesday, on Palestinians coming into Israel from the West Bank and Gaza Strip.