RAMALLAH, West Bank ? Facing pressure from the United States, Europe and his own people, Palestinian leader Yasser Arafat agreed Thursday to have presidential and parliamentary elections within six months.

Arafat’s decision came as Palestinian legislators mounted their most high-profile challenge yet to the Palestinian leader, calling for elections within a year and a new Cabinet within 45 days.

Early Friday, violence erupted in the West Bank. More than 20 Israeli tanks and other armored vehicles entered the Palestinian city of Jenin before dawn and soon after, gunfire and explosions were heard, Palestinian residents of the city said.

There was no immediate word on casualties, and the Israeli military declined immediate comment.

Previous attempts to reform Arafat’s administration have led to few significant changes, with Arafat ignoring laws passed by parliament as well as decisions by the judiciary. The proposed election would be the first time Arafat faced the voters since he was overwhelmingly elected president of the Palestinian Authority in 1996.

“President Arafat has set a program for reform and changes,” said Ahmed Abdel Rahman, secretary general of the Palestinian Cabinet.

“The core of the changes will be conducting general elections in a period that will not exceed four to six months,” he said, adding that Arafat has called for a meeting of the Central Elections Committee within two days.

Israeli officials were skeptical of the proposals.

“What’s clear is that any Palestinian leadership would have to, first and foremost, renounce terror as a strategic option,” said David Baker, an aide to Israeli Prime Minister Ariel Sharon. “Until now, terror and the Palestinian Authority have been joined at the hip.”

Arafat’s decision came amid questions about his popularity among his people. With the Palestinian economy in shambles and society reeling from a crushing Israeli incursion into Palestinian areas, Palestinians were pressing for reforms to an administration widely regarded as corrupt.

In a speech Wednesday to Palestinian legislators, Arafat echoed the calls for reform but gave no details.

Palestinian legislators quickly put together a reform plan Wednesday that called for elections and a smaller Cabinet and approved it Thursday. Soon afterward, Abdel Rahman announced Arafat’s own plans to have elections.

Legislators from Arafat’s Fatah movement also had demanded the creation of the post of prime minister and called for empowering it with the day-to-day operations of the Palestinian Authority. Arafat’s proposal made no mention of a prime minister.

The legislators also called for streamlining the Palestinian Authority’s eight security services. Arafat’s proposal did not address this issue.

Arafat has run the Palestinian territories virtually unchallenged since Israel permitted his return from exile eight years ago.