WASHINGTON — Congress this morning approved a two-month renewal of payroll tax cuts for 160 million workers and unemployment benefits for millions, handing President Barack Obama a convincing victory for his jobs agenda.

Back-to-back voice vote approvals of the measure by the Senate and House capped a retreat by House Republicans who had insisted that a full-year bill was the only way to prevent an immediate tax increase on Jan. 1.

The measure passed despite lingering grumbling from tea party Republicans. It buys time for negotiations early next year on how to finance a yearlong extension of the 2 percentage point Social Security payroll tax cut.

It will keep in place a salary boost of about $20 a week for an average worker making $50,000 a year and prevent almost 2 million unemployed people from losing jobless benefits averaging $300 a week.