WASHINGTON—Top Senate Democrats are expected to introduce legislation this week, perhaps as soon as Tuesday evening, that would provide a stopgap, temporary extension of federal COBRA health care premium subsidies, Washington observers say.

Details still are being worked out, but the extension likely would be between 15 and 30 days, observers say.

The measure, expected to be introduced by Senate Majority Leader Harry Reid, D-Nev., would extend the federal premium subsidy to employees involuntarily terminated from March 1 through either March 15 or March 30, depending on the length of the extension lawmakers decide on. The subsidy pays 65% of an individual’s COBRA premiums for up to 15 months.

Without the extension, employees laid off after Feb. 28 would not be eligible for the subsidy.

The short extension would buy time while Democratic legislators develop a broader bill that would include a longer COBRA subsidy extension.

“A short extension serves a dual purpose. It would allow more time to bring up the larger jobs agenda bill, including a COBRA subsidy extension, while avoiding the expiration of eligibility on Feb. 28,” said Frank McArdle, a consultant with Hewitt Associates Inc. in Washington.

An extension of the COBRA premium subsidy through May 31 had been part of a bipartisan jobs bill previously put together by top members of the Senate Finance Committee. But Sen. Reid stripped out the COBRA provision and numerous others in favor of a more narrowly focused jobs bill, which the Senate soon is expected to approve. After that, several additional jobs-related bills are expected to be proposed by Sen. Reid, including one that would include a multi-month COBRA premium extension provision, observers say.

Just over a year ago, Congress passed a nine-month federal COBRA premium subsidy as part of a massive economic stimulus bill. The subsidy was available to employees laid off from Sept. 1, 2008, through Dec. 31, 2009.

Then, last December, federal legislators, as part of bill appropriating funds for the Department of Defense, extended the subsidy to employees laid off through Feb. 28, while increasing the length of the subsidy to 15 months from nine months.