WASHINGTON — Legislation extending unemployment insurance for the long-term jobless faces a key test vote in the Senate, its momentum helped by about 60 popular tax breaks for individuals and businesses that expired at the end of last year.

The measure also prevents doctors from absorbing a crippling cut in Medicare payments, extends health insurance subsidies for the unemployed and gives cash-starved states help with Medicaid, the federal-state program providing health care to the poor and disabled.

The unemployment insurance alone — to provide weekly unemployment checks averaging above $300 to people whose core 26-week benefit package has run out — will cost $66 billion through December. In some states, people are eligible to receive benefits for up to 99 weeks.

The bill, and the test vote today, demonstrate the difficulty Democrats face as they focus on jobs. It doesn't include new ideas for boosting jobs, but instead reprises elements of last year's $862 billion economic stimulus bill, which is earning mixed reviews from voters. Extending those provisions has produced a far more expensive measure than a separate so-called jobs bill Democrats hope to soon send to President Barack Obama.