A major Minnesota union asked Sen. Al Franken (D-Minn.) to reconsider his opposition to AT&T’s proposed acquisition of T-Mobile USA in a letter on Thursday.

The Minnesota AFL-CIO argued T-Mobile is a dying company that its current owner, Deutsche Telekom, wants to sell. The group claimed AT&T is more friendly to unions than the other potential buyer, Sprint.

{mosads}Sprint’s “anti-labor, outsourcing and offshoring actions are infamous,” wrote Minnesota AFL-CIO President Shar Knutson and Steve Hunter, the group’s secretary-treasurer.

AT&T has the largest full-time unionized workforce in the country.

“Through this merger, more than 20,000 T-Mobile employees will have the opportunity to choose whether to have a voice in the workplace through union representation and a chance for the improved job security, collective bargaining and workplace protections that representation brings,” the labor group wrote.

The letter also pointed to the potential job boost from $8 billion in infrastructure investments that AT&T has promised to make if the merger is approved.

“This private investment in infrastructure build-out should result in immediate job creation along with a subsequent boost to the economy as more Americans have access to high-speed broadband,” the AFL-CIO wrote.

Franken announced his opposition to the deal last month. He argued it would stifle competition, cost jobs and lead to higher prices for consumers.

The Federal Communications Commission and the Justice Department are reviewing the merger.