AT&T’s purchase of T-Mobile must be blocked on antitrust grounds, Sen. Herb Kohl declared today. The chair of the Senate subcommittee on Antitrust, Competition Policy, and Consumer Rights released a letter urging the FCC and Justice Department to step in before the two phone companies get hitched, the Wall Street Journal reports. The merger, he warned, “would likely cause substantial harm to competition and consumers, would be contrary to antitrust laws and not in the public interest.” The Senate is powerless, however, to interfere directly in the transaction. (More AT&T stories.)