WASHINGTON (AP) -- Capping months of months of struggle, House Democrats cleared an abortion-related impasse blocking a vote on sweeping health care legislation late Friday and officials expressed optimism they had finally lined up the support needed to pass President Barack Obama's top domestic priority.

A vote was expected on the legislation on Saturday, after Obama's scheduled midmorning trip to the Capitol complex to make one final pitch for its approval. The bill is designed to spread coverage to tens of millions who now lack it and ban insurance industry practices such as denying coverage on the basis of pre-existing medical conditions.

Under the arrangement, Reps. Bart Stupak of Michigan, Brad Ellsworth of Indiana and other abortion opponents were promised an opportunity to insert tougher restrictions into the legislation during debate on the House floor.

The leadership's hope is that no matter how that vote turns out, Democrats on both sides of the abortion divide will then unite to give the health care bill a majority over unanimous Republican opposition.

The plan emerged from hours of meetings presided over by House Speaker Nancy Pelosi and involving lawmakers on both sides of the abortion issue and officials from the U.S. Conference on Catholic Bishops.