The White House-backed drive for a healthcare bill picked up steam Thursday, propelled by a favorable report on its price tag and positive comments by some key players. But big hurdles remained, including disagreements among Democrats on how to finance the legislation. Sen. Charles Schumer revived a push for a public health insurance plan to compete with private insurers, proposing a federal plan that states could opt out of. Senate and White House negotiators are looking at the Schumer idea and others as they craft a bill to bring to the Senate floor.