House Democrats locked in two more votes on Wednesday as they inched toward the majority they need to pass health care legislation, giving them added confidence as they worked out the last details of the bill and girded for a historic showdown as soon as this weekend. Behind the scenes, Democratic leaders were still working to secure backing for the legislation from among roughly three dozen members of the party whose votes are considered to be in play, even as they awaited a final price tag on the bill from the Congressional Budget Office. But they sought to portray the measure as gaining momentum from the public declarations of support from two Democrats: Rep. Dennis J. Kucinich of Ohio, who had previously opposed it, and Rep. Dale E. Kildee of Michigan, who had been among a group seeking tighter restrictions on the financing of insurance covering abortions. Democratic leaders say they have not nailed down the 216 votes they need for passage, but they are pressing ahead in the belief that they can get them. The House Democratic leader, Rep. Steny H. Hoyer of Maryland, said the House could take a final vote on the legislation by Sunday. But House Republicans said they still believed they could block the bill, a top priority for President Barack Obama and Speaker Nancy Pelosi. Under a two-step plan devised by House Democratic leaders, the House would approve the health care bill passed by the Senate in December, then make changes in a separate bill using a procedure known as budget reconciliation to avoid the threat of a filibuster in the Senate. Republicans like Rep. David Dreier of California have accused Democrats of ducking a straight-up vote on the Senate bill, which has provisions that many House Democrats do not like. Rep. John A. Boehner of Ohio, the House Republican leader, said Republicans were engaged in a variety of activities to stir opposition to the health care bill in the home districts of Democrats considered vulnerable in the November elections. 'We are going to do everything we can to put the pressure on these guys because they are going to have to choose,' said Boehner. 'Are they going to vote with Nancy Pelosi and the president, or are they going to vote with their constituents?' 'It's going to be a wild ride,' Boehner predicted. 