WASHINGTON — The multimillion-dollar lobbying effort to expand a children's health insurance program is creating some strange bedfellows.

Seniors are joining with doctors. Unions with health providers. The pharmaceutical industry with one of its biggest critics, the advocacy group Families USA. They share the same goal — expanding the State Children's Health Insurance Program.

A bill moving through the Senate would add $35 billion to the program over the next five years, raising total spending to $60 billion. House leaders will likely call for adding $50 billion to the program.

The Bush administration has recommended a $5 billion increase.

AARP, with its 39 million members, and the American Medical Association plan to make it uncomfortable for Republican lawmakers to agree with the administration's position. Yesterday, the two organizations announced a lobbying campaign they said will likely exceed $2 million.

They back the House legislation for two reasons: It would expand health insurance to more children and eliminate a 10 percent cut in reimbursement rates for doctors who see Medicare patients. The cut would kick in Jan. 1, unless Congress intervenes.

The House legislation would pay for those changes by increasing tobacco taxes and lowering payments to insurers who administer health plans for Medicare beneficiaries. The two groups say the insurance companies are overpaid.

The two groups will spend about $1.3 million for an initial wave of television ads that will run nationwide. The groups also will use direct mailings to ask members to meet with lawmakers during the August recess.

"This is a substantial effort we're undertaking in order to get this legislation passed," Bill Novelli, the AARP's chief executive officer, said yesterday.

Just a day earlier, the Partnership for Quality Care, an organization of labor unions and health providers, unveiled an ad in which children, parents and healthcare providers explain that an increased tobacco tax will not only help more children become insured, but would also decrease smoking.

The group was the first to use ads that clearly advocate for a way to pay for SCHIP's expansion.

Kate Navarro-McKay, spokeswoman for the partnership, said the ads would run in 13 congressional districts — eight Democratic districts and five Republican districts, over two weeks. The cost: $1.2 million.

The ads were not designed to pressure lawmakers so much as to appeal for bipartisan leadership on the issue. The 13 were chosen because of their potential to be leaders on the issue, she said.