(Reuters) - U.S. health insurer Anthem Inc ANTM.N said on Monday it will no longer offer Obamacare plans in Nevada's state exchange and will stop offering the plans in nearly half of Georgia's counties next year.

FILE PHOTO: The office building of health insurer Anthem is seen in Los Angeles, California February 5, 2015. REUTERS/Gus Ruelas/File Photo

The moves come after Republican senators last month failed to repeal and replace Obamacare, former President Barack Obama’s signature healthcare reform law, creating uncertainty over how the program providing health benefits to 20 million Americans will be funded and managed in 2018.

Hundreds of U.S. counties are at risk of losing access to private health coverage in 2018 as insurers consider pulling out of those markets in the coming months.

Nevada had said in June that residents in 14 counties out of 17 in the state would not have access to qualified health plans on the state exchanges. Anthem’s decision to leave the state entirely does not increase the number of “bare counties” in the state, Nevada Insurance Commissioner Barbara Richardson said in a statement.

The insurer will still offer “catastrophic plans,” which can be purchased outside the state’s exchange and are only available to consumers under 30 years old or with a low income.

Anthem also said it will only offer Obamacare plans in 85 of Georgia’s 159 counties. It said the counties it will continue to offer the plans in are mostly rural counties that would otherwise not have health insurance coverage for their residents.

It said these changes do not impact Anthem’s Medicare Advantage, Medicaid or employer-based plans in either state.

The company said last week that it will pull out of 16 of 19 pricing regions in California in 2018 where it offered Obamacare options this year.

Anthem blamed the moves in part on uncertainty over whether the Trump administration would maintain subsidies that keep costs down.

U.S. President Donald Trump last week threatened to cut off subsidy payments that make the plans affordable for lower-income Americans and help insurers to keep premiums down, after efforts to repeal the law signed by his predecessor, President Barack Obama, failed in Congress.

Trump has repeatedly urged Republican lawmakers to keep working to undo Obama’s Affordable Care Act.