ON THURSDAY, representatives of the federal contractors who built HealthCare.gov stated the obvious in front of a House panel: The government did not leave enough time to test the Web site before its error-filled Oct. 1 launch. The next question, a growing number of lawmakers now insist, is whether the government will leave people enough time to sign up for coverage before they are fined for lacking health insurance.

“Given the existing problems with the website,” Sen. Jeanne Shaheen (D-N.H.) wrote to President Obama on Tuesday , “I urge you to consider extending open enrollment beyond the current end date of March 31, 2014.” Nine other Senate Democrats signed a similar letter. The move would delay the penalty for lacking coverage, which is set to kick in next spring. Other lawmakers want to go further, canceling the penalty for all of next year.

Neither proposal is a good idea.

Despite the intolerable failure of the Obama administration to warn the country that HealthCare.gov would not work at launch, there is still plenty of time for the government to make the required fixes. The first major deadline is not until Dec. 15, when people have to apply to obtain insurance coverage that starts on Jan. 1. People don’t need insurance then, though, to avoid the penalty. Resolving a point of confusion, the Obama administration clarified Wednesday that anyone signed up by March 31 will not have to pay any penalty. That’s more than five months from now.

IPad-toting members of Congress in Thursday’s hearing offered differing accounts about the current ease of using HealthCare.gov, but the site has improved since Day One. Even if it takes some weeks more to get the site in reasonable order, insurance buyers will probably have plenty of time to obtain coverage before running afoul of the penalty.

Why not delay the penalty, just in case? Attacking the so-called individual mandate makes for great politics but following through on the delay would destabilize the new and vulnerable insurance market. Next year, the law will oblige insurance companies to accept pretty much anyone, regardless of age or health. The trade-off is that everyone will be required to buy into the system so that insurance companies can have enough healthy customers to keep premiums for everyone reasonable. The penalty against individuals lacking health-care coverage is a crucial tool in the effort to drive people into the new system. Delay it, and you’ll get fewer people signing up in the first part of next year, and insurance companies will demand, with good reason, to renege on the rates they are offering for next year’s coverage. At present, lawmakers do not need and should not attempt to make that outcome any more likely.

On Friday, Jeffrey Zients, the site’s new point man, said the HealthCare.gov system will work by December. He and everyone else had better hope that its bungled rollout hasn’t turned off too many people permanently. If Congress wants to help, it could make sure the necessary funds are appropriated to complete the Affordable Care Act’s implementation.