A Trump appointee has diverged from the White House and admitted that more people attended Barack Obama’s 2009 inauguration than Donald Trump’s.

Director of the Office of Management and Budget nominee Mick Mulvaney admitted to the observable fact during his Senate confirmation hearing.

"I'm not really sure how this ties to OMB," Mr Mulvaney said. He added that "from that picture, it does appear that the crowd on the left-hand side [for Mr Obama's 2009 inauguration] is bigger than the crowd on the right-hand side."

The subject of crowd size has been a topic of heated debate the past few days, as White House Press Secretary Sean Spicer declared during his first statement to the press, “that was the largest audience to witness an inauguration, period”.

Trump senior advisor Kellyanne Conway later told MSNBC that Spicer was not false in his statements, but that he presented “alternative facts” on the issue. The comments sparked concern with pundits and on social media over what the administration considers facts even when presented with hard evidence.

At the start of the confirmation hearing on Tuesday Senator Tom Cotton of Arkansas introduced Mr Mulvaney, a member of the House of Representatives from South Carolina, as a “bold truth-teller.”

Sean Spicer: "I think sometimes we can disagree with the facts"

Oregon Senator Jeff Merkley jumped on the comment and asked Mulvaney indicate which was the larger crowd size, 2009 or 2017. Mr Merkley displayed a large posterboard featuring side-by-side photographs of the National Mall on the day in question. The picture from 2009 is full of people, while the 2017 picture shows gaps where the white protective cover on the ground shows through in several sections.

Mr Mulvaney said he was not familiar with Mr Spicer’s claims but assured Mr Merkley that as budget director he would be “deadly serious about giving you hard numbers.”

During a White House press briefing, Mr Spicer added to his initial comments being questioned about his crowd size claim.

He said that when he referred to “audience” he meant that to include people in attendance as well as television and online viewers.

According to the Nielsen Company, Mr Trump’s inauguration drew in approximately 31 million viewers – far fewer than the 41.8 million who watched Ronald Reagan take the oath of office in 1981. About 37.8 million people watched Mr Obama’s first inauguration.