WASHINGTON - Democrats trying to push President Obama's health-care overhaul plan through the Senate got a sober warning yesterday that costs will keep going up and proposed Medicare savings may harm the program.

A new report from government economic analysts at the Health and Human Services Department found that the nation's $2.5 trillion annual health-care tab won't shrink under the Democratic blueprint that senators are debating. Instead, it would grow somewhat more rapidly than if Congress does nothing.

More troubling was the report's assessment that the Democrats' plan to squeeze Medicare for $493 billion over 10 years in savings relies on specific policy changes that "may be unrealistic" and could lead to cuts in services. The Medicare savings are expected to cover about half the nearly $1 trillion, 10-year cost of expanding coverage to the uninsured.

In still more bad news, the report starkly warned that a new long-term-care insurance plan included in the legislation could "face a significant risk of failure" because it would attract people in poor health, leading to higher and higher premiums, and eventually triggering an "insurance death spiral."

The one bright note: The bill would provide coverage to 93 percent of U.S. residents, reducing the number of uninsured people by about 33 million, the report said.

The analysis from the Office of the Actuary, which does long-range cost estimates for Medicare, was prefaced by a disclaimer saying it does not represent the official position of the Obama administration. Unlike estimates from the budget office, which have mainly focused on the legislation's impact on the federal deficit, the actuaries looked at total public and private costs over the next 10 years.

The analysts also used their years of experience with Medicare's finances to make a judgment call on whether the cuts proposed in the Democratic bills are politically sustainable. When previous Congresses have cut Medicare too deeply, providers have usually convinced lawmakers in subsequent years to restore at least some of the money. That same scenario is playing out this year as doctors try to persuade Congress to permanently repeal automatic spending cuts that would reduce their Medicare fees 21 percent next year.

The actuaries' analysis of the Senate bill echoes their previously released reports about the House bill. It addresses core provisions of both bills, and is unlikely to be affected by the latest changes Senate Democrats are proposing.