WASHINGTON -- The Senate has voted to jump-start a stalled immigration measure to legalize millions of unlawful immigrants.

The 65-34 vote will allow the debate to resume, two weeks after 45 senators voted to kill the bill. The debate will likely continue this week. But the bill still faces formidable obstacles in the Senate, including bitter opposition by Republican conservatives.

In spite of the lashing the immigration legislation has taken on Capitol Hill, President George W. Bush has remained optimistic about winning Senate approval before the week is over.

He said the administration plans to start focusing on the House, as soon as the Senate passes the bill. It would pave the way for millions of undocumented immigrants to become citizens.

But conservative critics of the bill are doing all they can to make sure it never makes it that far. They said their plans to mire the legislation down in Senate rules and procedures are moving along.