The White House on Tuesday delayed for one year the new requirement that businesses provide health insurance to employees under the Affordable Care Act, a fresh setback for President Barack Obama's landmark health care overhaul just as it enters a critical phase.

The provision, commonly known as the employer mandate, calls for companies with a workforce of 50 or more to provide affordable, quality insurance to employees or pay a $2,000 fine per worker. Business groups had objected to the provision, which now will take effect in January 2015.

The decision comes as Obama is working to secure his domestic legacy, urging Congress to pass an overhaul of immigration laws and using his executive powers to combat climate change. With the prospects for immigration reform uncertain in the House — and new environmental regulations still more than a year way — implementation of the 2010 health care law has assumed even greater importance.