US President Barack Obama signed into law a compromise bill extending a payroll tax cut and jobless benefits through 2012, after a bitter partisan fight over how to pay for it.

Congress approved the bill on Friday with broad bipartisan support, ending the contentious battle over a measure aimed at boosting the tepid US recovery -- and giving Obama a key election-year victory.

The US president, who is seeking re-election in November, signed the bill in the Oval Office, a White House statement said.

"Extending the payroll tax cut was a critical step for middle class families, but we still have a lot more work to do. So get ready," Obama senior advisor David Plouffe said in an email.

Obama made passage of the extension through the end of the year a top priority, but the measure was long stalled in a deeply divided Congress over how to pay for it.

The US president had encouraged supporters to send in letters explaining what the extra money would mean to them personally.

The plan extends a cut in the Social Security tax rate -- from 6.2 to 4.2 percent -- for another 10 months, and unemployment benefits through 2012.

It will mean a salaried worker making an annual $50,000 will be getting about $1,000 more in take-home pay over the course of the year.

The measure also puts off cuts in payments to doctors by Medicare, the national health insurance program for the elderly, until after the November elections.

The cost of the package has been estimated at $150 billion.