The recent election of Benjamin "Bibi" Netanyahu as the top opposition leader in Israel's government leaves an already weakened Prime Minister Ehud Olmert increasingly vulnerable on the peace front. Mr. Netanyahu, an articulate and outspoken former prime minister, has built his reputation as a hard-liner who supported Israeli settlers in the West Bank and opposed the withdrawal of Israeli troops from Gaza. His stated intention to return to the prime minister's office should guarantee his role as provocateur in any attempt to negotiate a peaceful settlement with the Palestinians.

Mr. Netanyahu's timing is fortuitous - for him. The Olmert government's poor handling of last summer's Lebanon war and other domestic problems have left Mr. Olmert open to attack from various camps in addition to Mr. Netanyahu and his Likud party, and with poll numbers that are worse than those of his friend in the White House.

And while the Bush administration is promoting a new peace conference for the fall, it's yet to be seen how much political muscle President Bush will exert to bring the region's stakeholders to the table and ensure substantive work gets done there. That leaves Mr. Netanyahu ample opportunity to challenge the process and attack Mr. Olmert.

In any peace deal, the number of Israeli settlements scattered throughout the Palestinian-populated West Bank will have to be significantly reduced. Their continued presence - and the Israeli military protection they require - would make it nearly impossible to envision, let alone establish, an independent Palestinian state that is contiguous. Mr. Netanyahu has been a vocal supporter of the settlers who claim the West Bank as the biblical land of Israel. He also favors the construction of a highway through the West Bank that would help settlement expansion east of Jerusalem. It's a road that undermines an equitable, negotiated peace deal.

Mr. Netanyahu's ascendancy makes it even more imperative that Mr. Bush and Secretary of State Condoleezza Rice live up to their commitment to a two-state solution that achieves an independent Palestine and a secure Israel.