WASHINGTON — David L. Cohen, the master salesman who runs the Comcast Corporation’s lobbying efforts, stood before a room full of Latino House lawmakers one morning in early December trying to convince them that they should embrace his $45 billion deal to acquire Time Warner Cable.

But as Mr. Cohen continued to talk — taking up much of the time set aside for the closed-door session — at least some of the assembled lawmakers began to wonder if his highly polished pitch was falling short.

“He was smothering us with attention but he was not answering our questions,” said Representative Tony Cárdenas, Democrat of California, who said that in the early stages of the deal he was open to supporting it if his questions were addressed satisfactorily. “And I could not help but think that this is a $140 billion company with 130 lobbyists — and they are using all of that to the best of their ability to get us to go along.”

The announcement Friday morning that Comcast was terminating its effort to take over Time Warner Cable, a plan that would have united the nation’s top two cable operators, ultimately collapsed because of clear signals that federal regulators were preparing to block it.