The new United States Congress may be mulling over how to overhaul one of President Obama’s signature achievements – the Affordable Care Act. But that doesn’t appear to be dissuading Arizonans from signing up for coverage. The enrollment season for the federal marketplace come to a close at the end of the month, and the head of the Centers for Medicare and Medicaid Services was in Phoenix this week.

The head of Medicare and Medicaid says Arizona’s making big strides under Obamacare and signups this year prove it. The acting Administrator Andy Slavitt was in Phoenix on Tuesday as the enrollment season draws to a close.

Despite concerns about rising premiums and competition, more than 183,000 Arizonans have selected plans in the marketplace so far. 

And the data show that year-over-year enrollments are up about 8 percent, Slavitt said. Factor in Medicaid, and Slavitt says the Affordable Care Act has far reaching benefits for more than 600,000 Arizonans.

And as Congress works to repeal the law, he cautions against changing Medicaid funding, for example, to a block grant, a concept many Republicans support.

“It puts a cap on the amount of money the federal government is going to invest in the Medicaid program in the state. So the state ends up in a position where it actually has to ration care," he said.

However, many conservatives argue this would actually give the state more flexibility to innovate and be efficient. Arizona was one of the conservative states that expanded Medicaid under Obamacare.