Just days before new online health insurance markets are set to open, the Obama administration Wednesday released a look at average premiums, saying rates in

most states are lower than earlier projected — and that 95 percent of consumers will have at least two insurers to choose from.

The report comes as part of a stepped-up administration effort to explain and defend the health law as congressional Republicans target it for defunding.

Until Wednesday’s report, little information was available about premium rates in most of the 36 states whose online health insurance marketplaces will be overseen entirely or partially by the federal government because state leaders opted out of running their own.

Data from the report offers the first look at rates coming on the Missouri marketplace.

The analysis released today showed huge variations among states: A family of four making $50,000 in Wyoming, for instance, would pay $1,237 a month on average for a midlevel plan before subsidies, compared to over $700 a month on average in Missouri. After subsidies are added in, however, the cost to both families would be $282 because the amount they pay is linked to their income, not to the cost of coverage.

While experts say premiums vary across the states and even within states, the analysis pegged the national average for an individual at $328 a month for a silver plan, before subsidies are factored in.

That’s less than the average $392 projection drawn from earlier data released by the nonpartisan Congressional Budget Office, which will mean savings to families as well as to the federal government for tax credits.

“For millions, these new options will make health insurance work in their budgets,” said Health and Human Services Secretary Kathleen Sebelius.