The top White House budget official said Sunday that President Trump is standing by his campaign-trail pledge not to overhaul Social Security -- but would still be happy to discuss it.

"I had a meeting with the president just the other day where as we walked over some of the numbers" about "what's driving the deficit," Office of Management and Budget Director Mick Mulvaney said on "Fox News Sunday."

"And I actually said, ‘Look, here's where it is, here's where it isn't, and Mr. president, I'm going to come back to you again and want to talk about entitlement spending," the former South Carolina congressman said.

"He said, ‘Look, I'm still not going to do it, but I'm happy to have the conversation. Same discussion we had in the spring, I promised people I wouldn't change Social Security, not going to do it.'"

Mulvaney said if tax reform passed in Congress, there could be enough economic growth and resulting tax income for the government to reduce the deficit.