WASHINGTON -- President Barack Obama's health-care overhaul faces an uncertain battle in the Senate after a narrow weekend victory in the House revealed the continuing divide among Democrats.

The bill passed by a 220-215 margin late Saturday after fractious debate. Thirty-nine Democrats voted against the measure. One Republican, Rep. Anh "Joseph" Cao of Louisiana, unexpectedly voted in favor.

In a Rose Garden appearance Sunday, Mr. Obama said he is "absolutely confident" a health-care bill also will pass through the Senate.

But its narrow passage in the House, where the Democrats have a large majority, underscores the difficulties ahead. Senate Democrats are struggling to agree on how to pay for the overhaul and whether to create a new public insurance plan to compete with private insurers, as the House did. Friction over how the bill treats abortion, which almost derailed the House vote, is likely to divide the Senate too.

"If the public option plan is in there, as a matter of conscience, I will not allow this bill to come to a final vote," Sen. Joe Lieberman (I., Conn.) said on Fox News Sunday.