US President Joe Biden will enforce a mandate that workers at US companies with at least 100 employees be vaccinated against Covid-19 or be tested weekly starting Jan. 4, spurring legal challenges from Republican governors who say Biden is overstepping his authority.

Within hours governors from Florida, Iowa and Indiana had vowed to fight the new rule, arguing it infringes on individual freedom.

Despite growing political opposition, the delayed roll-out of the mandate offered a reprieve to businesses facing labor shortages during the holiday season. Biden's related decision to push back a deadline for federal contractors to the same date suggested the White House accommodated requests from companies and industry groups.

- Reuters -