Acting Prime Minister Ehud Olmert briefed the US last week on his plan to impose Israel's final borders with the Palestinians if efforts to resume peace talks fail, an Olmert spokesman said Sunday. Backing from Washington, Israel's closest and most powerful ally, would be critical for any major initiative. "They neither approved nor objected to it," said spokesman Asaf Shariv, adding that an Olmert aide presented the plan to a US official before Olmert disclosed it in published interviews last week. US Embassy spokesman Stewart Tuttle was unable to confirm the report. In the interviews, Olmert said he planned to withdraw from much of the West Bank and parts of Jerusalem by 2010. The plan, which also calls for beefing up major settlement blocs Israel would retain, falls well short of Palestinian claims to all of the West Bank. He said he expected to win US and broader international support for the effort, which he expects to launch after Israel's March 28 elections. Polls show Olmert's Kadima Party easily winning the vote. Washington, the main architect of the "road map" peace plan, supports a negotiated settlement of the Israeli-Palestinian conflict, and not another unilateral move like last summer's withdrawal from the Gaza Strip and four small West Bank settlements. President Bush has backed Israel's claims to keep some settlement blocs, but US officials have reacted coolly to Israeli claims on the Ariel settlement bloc, deep inside the West Bank, and the Jordan River Valley.