WASHINGTON — The Obama administration will soon take on a new role as the sponsor of at least two nationwide health insurance plans to be operated under contract with the federal government and offered to consumers in every state.

These multistate plans were included in President Obama’s health care law as a substitute for a pure government-run health insurance program — the public option sought by many liberal Democrats and reviled by Republicans. Supporters of the national plans say they will increase competition in state health insurance markets, many of which are dominated by a handful of companies.

The national plans will compete directly with other private insurers and may have some significant advantages, including a federal seal of approval. Premiums and benefits for the multistate insurance plans will be negotiated by the United States Office of Personnel Management, the agency that arranges health benefits for federal employees.

Walton J. Francis, the author of a consumer guide to health plans for federal employees, said the personnel agency had been “extraordinarily successful” in managing that program, which has more than 200 health plans, including about 20 offered nationwide. The personnel agency has earned high marks for its ability to secure good terms for federal workers through negotiation rather than heavy-handed regulation of insurers.