WASHINGTON — House Democrats are scrambling to secure enough support to pass President Barack Obama's historic health overhaul initiative, working to soothe last-minute concerns from rank-and-file Democrats ahead of a make-or-break vote.

Voting is set for Saturday on the 10-year, $1.2 trillion legislation that embraces Obama's goals of extending health coverage to tens of millions of uninsured Americans and putting tough new restrictions on insurance companies.

Obama was set to make a personal appeal to the Democratic rank and file in a visit Friday to Capitol Hill. That was called off late Thursday after the shootings at Fort Hood, Texas, and rescheduled for Saturday.

Action on health legislation was slowed as senators waited for the Congressional Budget Office to weigh in on a bill written by Majority Leader Harry Reid in consultation with the White House and key committee chairmen. Senate votes could slip until next year, but in the House Democratic leaders pressed forward.

They expressed optimism that when it came time to vote, they'd have the majority needed to prevail in the 435-seat House.

Asked Thursday if she had the votes, Speaker Nancy Pelosi replied: "We will."

Pelosi and other Democratic leaders were finalizing language to bar federal funding of abortion and resolving a flare-up over the treatment of illegal immigrants in the legislation that had Hispanic lawmakers up in arms.

Members of the Congressional Hispanic Caucus object to a provision in the Senate legislation — backed by the White House — that bars illegal immigrants from buying health insurance within a proposed new marketplace, or exchange, even if they use their own money to buy from private companies.