WASHINGTON — Support is building slowly behind President Barack Obama's health care legislation in the House, the result of intense lobbying and politically targeted changes aimed at reassuring waverers and winning over critics.

Obama himself will talk up the sweeping overhaul in a midday speech today in Virginia, his fourth outside-the-Beltway event in two weeks as he scrambles to rally the public ahead of a climactic vote this weekend.

On Capitol Hill, congressional leaders were focusing on those rank-and-file Democrats, including moderates and opponents of abortion, who remained undecided after the release Thursday of a final package of changes to the massive 10-year, $940 billion legislation.

Obama postponed until June a planned Asia trip that was set to begin Sunday, allowing him to stay in town for the House vote on Sunday and action next week in the Senate.