How to summarize ACA exchange failures re: Little Marco's 2014 poison pill risk corridor amendment

WASHINGTON — A little-noticed health care provision slipped into a giant spending law last year has tangled up the Obama administration, sent tremors through health insurance markets and rattled confidence in the durability of President Obama’s signature health law.

The attack stems from two years of effort by Senator Marco Rubio and others in Congress to undermine a key financing mechanism in the law. So for all the Republican talk about dismantling the Affordable Care Act, one Republican presidential hopeful has actually done something toward achieving that goal.

Mr. Rubio’s efforts against the so-called risk corridor provision of the health law have hardly risen to the forefront of the race for the Republican presidential nomination, but his plan limiting how much the government can spend to protect insurance companies against financial losses has shown the effectiveness of quiet legislative sabotage.

The risk corridors were intended to help some insurance companies if they ended up with too many new sick people on their rolls and too little cash from premiums to cover their medical bills in the first three years under the health law. But because of Mr. Rubio’s efforts, the administration says it will pay only 13 percent of what insurance companies were expecting to receive this year. The payments were supposed to help insurers cope with the risks they assumed when they decided to participate in the law’s new insurance marketplaces.