WASHINGTON—President Obama Tuesday night signed into law legislation that provides a stopgap, 31-day extension of federal subsidies of COBRA health care premiums.

The measure was approved earlier Tuesday by the Senate on a 78-19 vote, while the House cleared it last week.

Under H.R. 4691, the 65%, 15-month premium subsidy for laid-off workers is extended to those involuntarily terminated from March 1 through March 31.

Without the extension, employees laid off after Feb. 28 would have been ineligible for the subsidy.

The measure also will allow employees to receive the subsidy if they first lost group coverage due to a reduction in hours and then were terminated after enactment of the legislation, if certain conditions are met.

Meanwhile, the Senate Wednesday will continue consideration of legislation, H.R. 4213, that would extend the premium subsidy to employees laid off through Dec. 31, 2010.