Critics of T-Mobile US and Sprint’s proposed merger ramped their rhetoric in hopes of killing the deal, as concessions made by the operators to address competition concerns reportedly failed to impress regulators at the Department of Justice (DoJ).

Ajit Pai, chairman of the Federal Communications Commission (FCC), backed the merger on Monday (20 May), after T-Mobile and Sprint revealed plans to spin off the latter’s Boost Mobile prepaid brand and pay hefty fines if they don’t fulfil a series of rural and 5G coverage promises.

However, Bloomberg reported officials at the DoJ, another key agency reviewing the transaction, were not convinced those conditions would be enough to resolve concerns around the deal’s impact on competition.

A number of US officials and industry associations voiced similar concerns in a series of statements released after the FCC announcement.

David Cicilline, chairman of an Antitrust Subcommittee in the House of Representatives, called Pai’s endorsement “deeply concerning”, adding “consolidation is a threat to progress and economic opportunity, not the driver of it”.

Shirley Bloomfield, CEO of NTCA-The Rural Broadband Association, said the deal is “far more likely to harm than help rural customers”, while the Rural Wireless Association blasted the concessions as “drastically insufficient to protect consumers” against the harms of market consolidation.

Bloomberg noted it is unusual for the DoJ and FCC to split on granting approval for a given deal.

Senior FCC officials said on a call with journalists the agency communicated its findings to the DoJ, but added it is normal for the agencies to announce their conclusions on different days.