Fox News anchor Sandra Smith was seen reacting in disbelief to a pundit casting doubts over the legitimacy of Joe Biden's election win over the weekend, echoing the Trump administration's claim of election fraud.

In a video that is being widely circulated on social media, Smith, the host of 'America's Newsroom' was seen rolling her eyes in shock as a guest refused to accept Biden as the president.

'What is Happening?'

Sandra Smith reaction
A still from the video that is being circulated on social media. Twitter

In the clip, Smith can be heard exasperatedly asking "what is happening" as DC-based lawyer Cleta Mitchell repeated Trump's unfounded claims of widespread voter fraud.

"I think everybody wants to know that this was done properly and legally and we can trust the results,' Mitchell, who was being interviewed by Fox News' Trace Gallagher, said. "And I think we have to look into every one of these concerns."

"Remember, just because CNN says, or even Fox News says that somebody's president doesn't make them president,' Mitchell added.

While Mitchell continued speaking, Smith, who thought she was off-air at the time, could be seen rolling her eyes and shaking her head in doubt. "What?," Smith can be heard saying, looking up in disbelief and appearing to be unaware that she was being picked up on a hot mic.

While Mitchell goes on, Smith then interjects in an angrier tone, "What is happening? Like, Trace, we've called it." Mitchell either was unable to hear Smith's reaction or chose to ignore it as she continued speaking without faltering. Watch the clip below:

The Trump campaign has launched a flurry of lawsuits alleging that voter fraud and irregularities affected the outcome of the election in battleground states, which saw Biden reach the 270 electoral votes required to secure the presidency.

Social Media Reactions

The video has now gone viral on Twitter with millions of views and thousands of comments from users who found Smith's reaction amusing, some of them turning the reaction into a meme.

"Her face should be considered as the national 'wut?!' reaction to trumpians," wrote one user, while another commented, "Her facial expression before she says "what? We've called it".. is PRICELESS."

Here are some of the reactions on Twitter: