The National Labor Relations Board, the federal government's main labor law enforcement agency, extended for the second time the public comment period for its planned rewrite of the Obama-era union "speedy election" rule.

The extension reflects the intense interest in the board's decision by both business groups and labor unions since the rewrite is expected to have a major impact on the success of workplace organizing efforts. Among other changes, the Obama rule required employers to give unions all worker contact information, regardless of whether individual workers wanted that.

The board extended the comment period to April 18. The original submission deadline was Feb. 12 and had been extended to March 19.

Under current law, when a union petitions to represent a workplace, the employer must give the union a list of all prospective voters — that is, workers — in that election. In 2014, the board, which then had a Democratic majority, expanded the requirement from a list of names and addresses to include personal phone numbers and email addresses, without asking the workers if they wanted that information shared.

The rule also limited employers' ability to raise objections during the election process and shortened the time period from when elections are scheduled to when they are held.

The changes, widely dubbed the "speedy election rule," were significant because they were believed to aid unions in their efforts to organize workers. Labor groups cheered the changes, saying they limited union-busting tactics by employers while businesses groups came up with their own term for it: the "ambush election" rule.

In December, the then-Republican-majority announced it would solicit comments on whether the rule should be kept or rescinded, the first step in officially rewriting it. The extensions suggest the volume of responses has been large.