WASHINGTON — The on-again, off-again threat from the White House to shatter the Affordable Care Act appeared to be on again Friday, as Politico reported that President Trump “told aides in a Tuesday Oval Office meeting that he wants to end” subsidies for people who buy health insurance on the state and federal exchanges.

The theory is audacious: Despite marking his fourth month in office, and despite the control his party holds over Congress, the plan from the president, party leaders, and Republican campaign groups is to blame any increase on premiums on the Democrats.

But so far, Republicans have stayed on message – and Democrats have struggled to draw attention to tremors in the insurance market that can be traced to the White House’s shaky management.

“It’s very clear that President Trump and Republicans here in Congress are not interested in improving the exchanges,” Sen. Chris Van Hollen, D-Md., said at a news conference last week. “President Trump said ‘The best thing, politically, is to let Obamacare explode.’ Here’s the thing: They’ve been doing the detonating from day one.”

At issue are several vital components of the ACA, and the response of insurers to the White House’s on/off signaling. In his first week as president, Trump signed an executive order neutering the individual mandate, absolving the IRS from trying to collect a penalty from people who declined to buy insurance.

The White House also briefly canceled advertising ahead of the ACA’s winter enrollment period – analysts argued that the decision cut down on new enrollees, even after the advertising started up again.

But the subsidies fight has always been seen by Republicans as a way to make the ACA unaffordable, thereby kick-starting the “death spiral” that the current funding system prevents. Out of power, Republicans sued to stop the subsidies, arguing that they were illegally paid out because Congress had not specifically appropriated the money that the Obama administration was distributing.

Today, the subsidies could be stopped either by that lawsuit’s success or by the president’s decision.

The wrinkle: Republicans are portraying any market failure not as a result of their management, but as the basic ACA structure self-destructing. When the American Health Care Act was resurrected, House Speaker Paul Ryan, R-Wis., led Republicans in citing the decision of Medica to pull out of Iowa’s exchange as proof of the ACA’s collapse.

“Iowa is down to one insurer,” Ryan said. “Now that one insurer is saying that it will have to pull out of 94 of 99 counties. This is happening right now! This is a crisis, and it is happening right now!”