An economic stimulus plan backed by U.S. President Barack Obama passed the Senate on Tuesday and moves toward difficult Senate-House of Representatives negotiations on compromise legislation. As expected, only three Republicans voted in favor of the plan, which passed on a 61-to-37 vote, and Republicans immediately said they will fight hard to preserve more than $108 billion in spending cuts made last week in Senate deal-making. Obama wants to restore cuts in funds for school construction jobs and help for cash-poor states. Those cuts are among the major differences between the $819 billion House of Representatives version of the stimulus plan passed two weeks ago and the Senate legislation costing $838 billion. The president has repeatedly warned of a deepening economic crisis if Congress fails to pass a job-creating stimulus bill soon. He wants to sign the legislation by this weekend. The Senate vote came as the Obama administration moved forward on another key component of its economic recovery plan. Treasury Secretary Timothy Geithner on Tuesday unveiled rules for $350 in financial rescue funds designed to help the sector as well as homeowners facing foreclosure.