Last week, Republican Governor Bill Haslam announced a plan to expand Medicaid in Tennessee. Republican governors in Wyoming and Utah have also put forward expansion plans in the past month. A recent Washington Post editorial argued that there is “no rational justification” for refusing to expand Medicaid.

Despite this claim there are many reasons to be wary of Medicaid expansion even as some Republican governors signal some measure of support. A recent government report found that many Medicaid patients have access to care problems, including difficulty getting an appointment to see a doctor and lengthy wait times. Due to a looming reduction in the rates Medicaid pays some doctors, access to medical care for Medicaid enrollees is likely to get worse next year.

In the report from the HHS Office of Inspector General, researchers posed as Medicaid patients and called managed care providers. They found that 51 percent of listed providers could not schedule an appointment. Some providers could not be found at the location listed, some were found but were not participating in the plan, while others were no longer taking new Medicaid patients.

Even those few who were able to get appointments faced lengthy average wait times. At 28 percent of providers offering appointments, enrollees had to wait longer than a month. At 10 percent, the wait exceeded two months. Many states have requirements that wait times must be shorter than a month, so the fact that so many would have to wait longer than that “raises further questions about enrollees’ ability to obtain timely access to care.”

‘Secret shopper’ surveys like this one are not a complete picture. Other research has found that Medicaid patients’ access to care is not significantly worse than comparable private coverage, but these studies have their own limitations. For example, a 2012 Government Accountability Office (GAO) report found lower levels of access to care problems among Medicaid enrollees. That report is based on data from 2008-2009, when Medicaid enrollment was only around 50 million; next year enrollment will be 15-20 million higher than that, so the GAO’s findings regarding access to care problems are not as applicable today. Medicaid expansion will further increase demand for health care services when enrollees already have problems getting access to care.

In an attempt to address this access to care problem, the Affordable Care Act included a temporary two-year bump to Medicaid reimbursement rates for primary care doctors. The Urban Institute estimates that this bump increased fees by roughly 73 percent on average and cost the federal government $5.6 billion through June 2014. This temporary pay increase is now set to expire at the end of the month.

To avoid this payment cut, some states are extending the Medicaid fee increase with their own funds, but others cannot come up with the money to pay for the extension. States that would see the biggest reductions are more likely to forego the extension. According to the study, the 23 states that so far do not plan to extend the increase will see a 47 percent reduction in Medicaid primary care fees. These non-extension states cover 71 percent of Medicaid enrollees.  Three out of the four states identified by the researchers as having below average acceptance of Medicaid patients among primary care physicians do not plan to extend the fee increase. The majority of Medicaid enrollees could see lower payment rates for doctors next year, and in some of these states the patients are particularly vulnerable to access to care problems.

The relationship between reimbursement rates and the percent of doctors seeing new Medicaid patients is not yet entirely understood, but a 2012 Health Affairs study found a positive correlation between the two. In states with higher Medicaid fees, more doctors accepted new patients, while fewer doctors accepted new patients in states with lower payment rates. The approaching payment cut could mean fewer doctors in many states will see new Medicaid patients at the same time demand for their services increases.

Medicaid enrollees already have problems getting access to care. Next year, higher enrollment and lower payments to primary care doctors will exacerbate these problems and should give states another reason to reconsider moving forward with Medicaid expansion.