WASHINGTON (Reuters) - A broad healthcare overhaul passed its first crucial test in the US Senate on Monday, with 60 Democrats voting to put President Barack Obamas top legislative priority on a path to passage by Christmas. In a middle-of-the-night vote in a snowbound US capital, Democrats unanimously backed the first in a series of three procedural motions to cut off debate and move the bill to a final vote by the night of Christmas Eve. Well get this passed before Christmas and it will be one of the best Christmas presents this Congress has ever given the American people, Democratic Senator Tom Harkin said. Mondays vote was the first test of whether Democrats could secure the 60 votes needed to overcome unified Republican opposition and muscle healthcare reform through the Senate. Republicans acknowledged they could not stop the bill, which would spark the biggest changes in the $2.5 trillion US healthcare system since the 1965 creation of the Medicare health program for the elderly. The impact of this vote will long outlive this one frantic, snowy weekend in Washington, Republican Senate leader Mitch McConnell said. This legislation will reshape our nation, and Americans have already issued their verdict-they dont want it. The bitter healthcare debate has consumed the US Congress for months and raised the stakes for Obama, with his political standing and legislative agenda on the line less than a year into his first term. Democrats were assured of victory on Saturday after their last holdout, Senator Ben Nelson, agreed to a compromise ensuring federal funds would not be used to pay for abortions and sending extra healthcare money to his home state of Nebraska. With 60 votes in hand, the only drama in the early Monday vote was whether all of the Democrats would make it through the snow-packed streets of Washington to the Capitol. What the American people ought to pray is that someone cant make the vote tonight, Republican Senator Tom Coburn said beforehand. The loss of even one Democrat would sink the plan in the 100-member Senate. Democrats control 60 votes, the exact number needed to overcome united Republican opposition. If the Senate passes the health bill, it must be reconciled with a version passed by the House of Representatives that has stricter anti-abortion language and a government-run insurance option dropped from the Senate bill to appease moderates. The merged bill must be passed again by each chamber before it is sent to Obama, but the final measure is unlikely to stray far from the Senate version given the difficulties in winning approval there.