Updated

House Republicans want the IRS to investigate whether AARP's lucrative insurance business violates its status as a tax-exempt organization.

The seniors lobby pushed for President Barack Obama's health care law, which was solidly opposed by Republicans. On Wednesday, three senior GOP lawmakers released a report estimating that AARP could make an added $1 billion over ten years on insurance plans with sales that are likely to pick up under the new law.

The report from Reps. Wally Herger of California, Charles Boustany of Louisiana and Dave Reichert of Washington found royalties on insurance sales are AARP's biggest source of revenue, far above dues paid by its 40 million members.

An AARP spokesman says support for the health care law was "in no way, shape, or form influenced by revenue considerations."