IN APRIL President Bush placed a high-risk bet on Israel's Ariel Sharon. He delivered, in writing, commitments of U.S. support for Israel's position on crucial outstanding issues for a settlement with the Palestinians, on the prospect that this would spur Mr. Sharon to carry out a proposed Israeli evacuation of settlements in the Gaza Strip and part of the West Bank. Mr. Bush's concessions have exacerbated an already parlous U.S. diplomatic position in the Middle East; Mr. Sharon, meanwhile, has suffered a string of reverses in his attempt to carry out the withdrawal. The administration might have responded by reassessing its reliance on a notoriously reckless leader. Instead, Mr. Bush has doubled up on his bet.

Over the past few days administration officials have let it be known that they will not object to the recent announcement by Mr. Sharon's government of more than 2,000 new housing units in Jewish settlements in the West Bank -- even though official administration policy opposes all such construction. The new homes are in settlements near Jerusalem and Tel Aviv that Israel expects to annex in any eventual peace agreement with the Palestinians -- an expectation Mr. Bush publicly supported as part of his gift package to Mr. Sharon in April. Their high-profile approval by Mr. Sharon is intended, in part, to split the fierce opposition movement that now blocks his Gaza plan, thereby raising the chances that the evacuation can begin as scheduled next year. That withdrawal would be a significant step toward a Middle East settlement and could help U.S. standing in the region.

For now, though, the United States will pay the price for its latest concession to Mr. Sharon, which has been headline news in Israel and around the Middle East. Once again the Bush administration will be seen as uncritically supporting a move by Israel to expand settlements regarded by the rest of the world as illegal, in contradiction to stated U.S. policy and commitments to allies in Europe and the Middle East. The fact that the White House has taken this position at a time when Mr. Bush is seeking support from pro-Israel voters in Florida and other closely contested states will raise reasonable questions about whether there are any grounds for his position other than electoral pandering. Administration officials would say that there are -- that they are confident that in the end Mr. Sharon will deliver. Maybe they are right, but the cost is growing.