President Obama on Thursday insisted that his under-fire health care blueprint is working just as planned, taking to the White House bully pulpit to defuse growing questions about the soundness of his signature legislative achievement.

The president stepped up his defense of the Affordable Care Act, as Republicans focus on his administration delaying until 2015 the requirement that employers provide insurance coverage to their workers or pay a fine.

Obama looked to paint his GOP rivals as so dead set on derailing the health law that they are ignoring its benefits.

“Yesterday, despite all the evidence that the law is working the way it was supposed to for middle-class Americans, Republicans in the House of Representatives voted for nearly the 40th time to dismantle it,” he said. “We’ve got a lot of problems in this country. There’s a lot of work that Congress needs to do … get a farm bill passed, get immigration reform done, make sure we’ve got a budget in place.”

Republicans on Wednesday voted to delay both the individual and employer mandates in the health care overhaul by a year, a symbolic gesture that has no chance of passing the Democratic-controlled Senate.

Ahead of open enrollment for Obamacare in October, the president is trying to convince younger, healthier people to participate in the program. Without such individuals enrolling, premium costs will soar.

The president trumpeted what is known as the 80-20 rule, which requires insurance companies to spend at least 80 percent of premium dollars on patient care and quality improvement. If companies don’t spend that amount, they are required to provide a rebate to customers.

Such rebates would average about $100 per family, the White House said.

Republicans were not moved by Obama’s appeal.

“If you’re a family … facing a $2,100 premium increase under Obamacare, then, really, what would you rather have: a check for $100 or so, or a way to avoid the $2,100 premium increase in the first place?” said Senate Minority Leader Mitch McConnell, R-Ky. “I think the answer’s obvious.”

Added House Speaker John Boehner, R-Ohio: “The picture that the president paints of his health care law looks nothing like the reality facing struggling American families.  They know that the law is turning out to be a train wreck.”

Obama touted a new Health and Human Services study showing that in the 11 states for which data is available, the lowest individual insurance premiums are 18 percent less expensive on average than was estimated previously by the Congressional Budget Office.

Critics counter that such a portrait does not present a complete picture of the repercussions of Obamacare, which is still disliked by most Americans, polls show.

Both Democrats and Republicans are making the same philosophical argument, just with wildly different conclusions. Both sides agree that most Americans aren’t fully aware of the true impact of the health law. Yet, Republicans say that public opposition to the president’s signature legislative achievement will intensify once provisions are fully implemented.

Obama told his supporters on Thursday to ignore arguments coming from conservatives.

“What I’ve heard is the same old song and dance,” Obama said, vowing to “blow through that stuff and just keep on doing the right thing for the American people.”