Federal Communications Commission Chairman Kevin Martin on Friday postponed a vote on the $79.3 billion merger of AT&T Inc. and BellSouth Corp. until Nov. 3 after agreeing to give two Democratic commissioners additional time to study last-minute fixes the companies have proposed.

Friday’s cancellation was the second time in two days the vote had been postponed. Martin sent a letter to Democrats Michael Copps and Jonathan Adelstein outlining his plan to open up the proceeding again and allow interested companies and consumer groups an additional 10 days to comment.