Washington regulators are expected to lay only a few obstacles in front of AT&T Inc.’s nearly $90 billion acquisition of BellSouth Corp. — none of them big enough to kill the merger.

Recognizing that neither the Department of Justice nor the Federal Communications Commission is remotely inclined to block a merger in the rapidly evolving telecommunications arena, rivals of the telephone giants and public advocates are hoping to convince regulators to at least saddle regulatory approval with more stringent protections for the companies’ customers. Opponents of the deal want to see more than was imposed on the recent mergers of AT&T Corp. and SBC Communications Inc. and Verizon Communications Inc. and MCI Inc.