Donald Trump's call for a temporary ban on Muslims entering the U.S. may be in the process of revision, hinted the head of the presumptive GOP nominee's campaign.

Trump campaign chairman Paul Manafort said the bombastic billionaire often sparks a conversation about a controversial topic, like the ban, by going to the "outer edges." But that doesn't mean he'll stay there.

"He's already started moderating on that," Manafort said, according to a report published Wednesday by the Huffington Post. "He operates by starting the conversation at the outer edges and then brings it back towards the middle. Within his comfort zone, he'll soften it some more."

Still, Manafort expects Trump's evolving tone to remain somewhere outside of "the middle."

"He'll still end up outside of the norm, but in line with what the American people are thinking," he said.

In the wake of the deadly San Bernardino, Calif., mass shootings at the end of last year, Trump called for a "total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what is going on." FBI officials say the two killers had been radicalized, citing jihadism as a motive.

Trump's comments ignited a flurry of criticism from political and religious leaders.