Congressional Republicans introduced legislation Wednesday that would roll back an Obama administration rule that allowed unions to gain footholds in businesses where they otherwise lacked enough worker support to have a regular union.

A long-standing federal rule required unions to get the majority support of all employees in a workplace before the government would recognize a union. The National Labor Relations Board, the main federal labor law enforcement agency, revised the rule in 2014, allowing the organization of smaller “micro-union” groups, provided that all those workers have a common connection. For example, instead of having to organize an entire department store, a union could organize just the workers in the sporting goods section.