(Photo by Will Stone - KJZZ)

Health-care advocates in Arizona have been pushing back against Republican plans to replace the Affordable Care Act in recent months.

As the U.S House gears up to vote on its replacement for the Affordable Care Act, critics of the GOP bill caution that Arizona could see a worse marketplace for individuals trying to buy insurance.

When open enrollment kicked off last year, the headlines in Arizona were dire — premiums spiking and an exodus of insurers from the marketplace.

The majority of consumers, however, didn’t see such dramatic increases because of tax credits. But the GOP’s American Health Care Act changes those credits, so they’re no longer based on income or where you live. In Arizona, that will mean on average about $3,500 less per person each year, said Kevin Griffis with the advocacy group Protect Our Care.

“They cut the tax credits much more heavily than they decreased the premiums. At the same time, they allow the insurers to charge people who are older enrollees as much as five times more,” said Griffis, who worked on health care under the Obama administration.

"It's the folks who are between 55 and 64 who stand to lose the most under the U.S. House bill," he said.

In Arizona, that could eventually increase costs close to $20,000 a year for that population.

While premiums would eventually come down, Griffis says that’s only because older people will be forced out of the marketplace.