, the website established for the federal health insurance marketplace, has been attacked by hackers 16 times.

WASHINGTON (Reuters) - As Americans scrambled to beat a deadline to sign up for insurance under President Barack Obama's health care law, the White House gave most consumers an extra day, until Tuesday, to obtain coverage that starts Jan. 1.

Over the weekend, government officials and outside IT contractors working on the online marketplace’s computer system made a software change that automatically gives people a Jan. 1 start date for their coverage as long as they enroll by 11:59 p.m. Christmas Eve, the Washington Post reported.

The last-minute move by the Obama administration to accommodate high demand came as it reported record traffic on, the federal enrollment website that struggled with glitches after its launch in October.

It was the latest impromptu change the administration has imposed on the program to address the fallout from a series of technical and political missteps.

Officials said the website received 1.2 million visits over the weekend and had surpassed 1 million additional visits by late afternoon on Monday. They said a call center took 200,000 calls from those seeking insurance under the Affordable Care Act, known as Obamacare.

The hustle to sign up in time for Jan. 1 coverage could help the Obama administration as it tries to patch up a botched rollout of the president's top domestic policy achievement, a law that requires most Americans to get health insurance or face fines.

Before the Monday rush, well over 1 million people had signed up for private coverage through - which serves 36 states - and 14 state-run marketplaces, according to state and federal estimates. The figure, though likely to climb by Christmas, shows how far the government has to go to reach an estimated 7 million people by the end of enrollment in March.