Sen. Jon Tester on Monday asked the state's insurance commissioner to provide transparency and an honest explanation to Montanans about why they might face higher health insurance costs this year.

In his letter to Commissioner Matt Rosendale, Tester addressed the concerns of 52,000 state residents who buy their health insurance on the marketplace and are having their coverage undermined by what Tester says is the Trump Administration.

“Your office plays a lynchpin role in ensuring Montanans do not pay more than a reasonable rate for their health coverage,” Tester wrote in a letter to Rosendale. “I encourage you to use your position to provide Montanans with as much transparency as possible so we can make sound decisions on how best to make quality health care more affordable.”

Tester said the Trump Administration has refused to say whether it will continue to provide vital cost-sharing reductions to insurers, which will lower deductibles, co-pays and out-of-pocket expenses for 22,000 state residents.

Commissioner Rosendale will be reviewing proposed health insurance rates, which are due to his office later this week. Tester said insurance commissioners in other states have asked their insurers to file two sets of proposed premiums, including rates that reflects continued cost-sharing reductions, and rates that apply if cost-sharing reductions end.

“Insurers have said that they could file reasonable premium proposals if they had confidence that cost-sharing reductions would continue,” Tester wrote. “The evidence is clear – without the certainty of continued cost-sharing reductions, insurers will charge higher premiums.”

Citing the uncertainty around these cost-sharing payments, leading health organizations have said this inaction will cause double-digit premium increases for 2018.

Standard and Poor’s confirmed that the markets were on track for stabilization, Tester said, but uncertainty over cost-sharing reductions and pending legislation could significantly increase premiums or drive insurers out of the marketplace altogether.

As part of his ongoing efforts to improve the Affordable Care Act (ACA), Tester also sent a letter to President Donald Trump offering to provide a rural perspective on how best to bring down health care costs and improve accessibility.