WASHINGTON — A group of Democratic senators are sounding the alarm over T-Mobile's proposal to acquire most of US Cellular, and asking the Justice Department and the Federal Communications Commission to closely scrutinize and consider challenging the deal. The $4.4 billion deal announced in May 2024 would allow T-Mobile to use part U.S. Cellular's wireless spectrum to improve its coverage in rural areas and give it access to four million new customers. In the letter, six Democrats wrote. that the plan would raise costs for customers and limit choices. "Additional consolidation in the market would have far-reaching effects, reducing choices for consumers, further concentrating wireless spectrum holdings,