WASHINGTON: A sweeping healthcare overhaul narrowly cleared its first hurdle in the US Senate on Saturday, with Democrats casting 60 party-line votes to open debate on the biggest healthcare changes in decades.

In the first Senate test for President Barack Obama's top domestic priority, Democrats unanimously backed a procedural motion to open debate over the opposition of 39 Republicans. Republican George Voinovich did not vote.

Democrats needed 60 votes to approve the motion in the 100-member Senate and had no margin for error - they control exactly 60 votes.