Citing a “volatile” market, the nation’s second-largest health insurer announced Wednesday it plans to pull out of ObamaCare exchanges in Indiana and Wisconsin next year -- a move that fueled GOP calls on Capitol Hill to upend the law.

Anthem Inc. said “planning and pricing for ACA-compliant health plans has become increasingly difficult due to a shrinking and deteriorating individual market, as well as continual changes and uncertainty in federal operations, rules and guidance, including cost-sharing reduction subsidies and the restoration of taxes on fully insured coverage.”

Earlier this month, Anthem said it would leave Ohio’s ACA market. The company’s pullback is symptomatic of the instability many insurers are facing when dealing with ObamaCare markets.

Republicans cited the latest news as they prepare to fast-track a vote on a replacement package -- something President Trump is eager to get through Congress.

“Obamacare is clearly collapsing, and we have to step in before more families get hurt. We are on a rescue mission to replace this collapsing law with a better system so that people have lower costs, more choices, and real peace of mind. We need to get this done," House Speaker Paul Ryan, who represents Wisconsin, said in response to the Anthem decision.

While the House has passed a replacement bill, Republican senators currently are working behind closed doors on a revised package that could deliver on Trump’s campaign promise to gut former President Barack Obama’s signature health care overhaul.

The bill's key components are expected to be unveiled Thursday.

Trump has also threatened to withhold funds that offset the costs for low-income people buying plans through the exchanges.

Anthem said in a statement it will offer an off-exchange medical plan in five counties across Indiana and one in Wisconsin.

Anthem’s shrinking participation will not affect the 4 million members in Anthem’s Indiana Blue Cross Blue Shield plans. The changes also do not affect Medicare Advantage, Medicaid or employer-based plans.

Anthem currently operates across 14 states.

MDwise Marketplace, another Indianapolis-based insurer, also announced Wednesday they would not offer individual plans next year.

Meanwhile, health insurance startup Oscar Insurance Corp. announced it would increase its participation in ObamaCare. Oscar was founded by Josh Kushner, the brother of Jared Kushner, Trump’s son-in-law and senior adviser.

Oscar will start selling ObamaCare plans in Tennessee next year and re-enter the New Jersey exchange, The Wall Street Journal reported. It will also expand coverage in California and Texas. Last week, Oscar announced it would start working with the Cleveland Clinic in Ohio.