It turns out that if Republicans wanted to stop ObamaCare in its tracks, they would have been better off getting out of the way.

With the government shutdown now a thing of the past, national attention has shifted to the nascent health-insurance exchanges created by ObamaCare — and their tumultuous debut.

The embarrassing stumble has placed President Obama once again on the defensive over his signature domestic policy achievement, forcing him to parry complaints and insist that improvements are on the way. And with Republicans still licking their wounds after the shutdown fight, the shaky start has given the president's foes renewed hope that they can still undercut the law behind a wave of public opinion.

Since going live October 1, — the online marketplace where users can shop for and purchase health insurance — has been plagued by glitches, sometimes crashing beneath the heavy load of would-be enrollees. Coverage under the Affordable Care Act begins January 1, but with the site mired in a technical limbo, millions of uninsured Americans may, for now, be unable to obtain coverage.

Critics of the health-care law have clamored to cast the sputtering rollout as indicative of the overall law's unwieldiness.

The site is an "unmitigated disaster," Rep. Phil Gingrey (R-Ga.) told Politico. "If the federal government is unable to manage this website, how can they possibly manage our country’s health-care system?"

Even Obama acknowledged the site had a terrible launch, saying in a speech Monday there was "no excuse" for the failure. However, he vigorously defended ObamaCare as a whole, saying the "essence of the law, the health insurance that's available to people, is working just fine."

Still, as many observers have pointed out, the fate of the law depends on uninsured Americans buying into the system. If people walk away from the exchanges disillusioned, then the entire law grows weaker.

If the ACA's website continues to struggle, and if public opinion of the law sours as a result, it could give Republicans an opportunity to mount a more successful challenge in the future. Republicans have, after all, pledged to continue fighting ObamaCare long after its implementation; Heritage Action CEO Michael Needham, whose group propelled the defund movement, predicted an ObamaCare repeal wouldn't come until 2017.

For now, Americans are willing to give the Obama administration a chance to work out some of the kinks. A Washington Post/ABC News poll released this week found that while a majority of Americans said the site's problems were indicative of a larger failing in the law, only one third said ObamaCare should be repealed.

Obama could quell much of the backlash by, quite simply, making ObamaCare work. He said Monday the White House was bringing in more tech experts to help retool the site, though he remained vague on what specific fixes were needed. Since anyone who enrolls in a new policy before December 1 will start receiving coverage in January, the administration has about a month to get everything working smoothly, according to The Washington Post's Sarah Kliff.

But the problems are so extensive they could take weeks, if not longer, to fix, requiring specialists to rewrite as many as 5 million lines of code, according to The New York Times. The administration reportedly asked if the site could be fully operational by November 1, a date coders deemed "unrealistic," the Times said.

Come March 31, Americans who still don't have insurance will face a tax. Conceding that fixes to the website might be so long in coming that the uninsured are left with little time to obtain coverage by that date, White House Press Secretary Jay Carney suggested the administration could ultimately delay the penalty.

Ring a bell? That's pretty much what some Republicans in the House wanted to do, after its initial "defund" strategy foundered.

In the meantime, the president's effusive remarks on the broader law, in the face of the website's glaring flaws, struck many as tone-deaf, potentially undercutting his sales pitch. Obama's comments were "far less contrite than they should have been," said Andrew Sullivan at The Daily Dish, adding the speech was rife with "positive rationalizations and excuses in a confusing technical lecture."

"He does not have the credibility to sell us on the ACA when he does not cop more aggressively to his own failure to stay on top of this most important domestic initiative," he wrote.

The ACA is no longer an abstract bogeyman. Now that the insurance exchanges are live, the battle over ObamaCare is finally beginning to have concrete metrics to indicate how well it's performing.

The administration hasn't fared so well to this point in framing the debate, and a continued failure to get the site up and running would only serve to reinforce what conservatives warned all along in the buildup to the shutdown: ObamaCare is a train wreck.