Donald Trump is taking heat for what has become his latest line of attack against Hillary Clinton: claiming the former secretary of state doesn't look like she belongs in the Oval Office.

"I just don't think she has a presidential look. And you need a presidential look. You have to get the job done," the Republican presidential hopeful told ABC News' David Muir in an interview over Labor Day weekend.

The comment drew immediate criticism from Clinton allies, including her running mate, Tim Kaine, who blasted Trump during a campaign stop on Monday.

"Here's my prediction: At the end of a second-term Hillary Clinton, Trump will be saying that same thing as he's hawking bottled water somewhere and we've forgotten he ever ran for president," the Virginia senator remarked.

Clinton's deputy communications director added to Kaine's criticism on Tuesday, noting that "this isn't the first time Donald Trump has had a problem looking at someone different from himself and actually seeing them."

"He questioned whether a distinguished judge could do his job because of his Mexican heritage. He looked at a mourning Gold Star mother and he made assumptions about her silence in grief. He looked at an accomplished anchor and suggested she was a 'bimbo,'" Christina Reynolds said in a statement released by the Clinton campaign. "And he looked at a sitting president and said he wasn't American."

"It's not surprising that Donald Trump doesn't think Hillary Clinton looks presidential," she added.

Some supporters of the former secretary of state suggested it was obvious that Trump was referring to her being a woman.

So...Clinton doesn't "look" presidential?

Because no president in 240yrs has been a woman?https://t.co/U7ObZQAwf8 pic.twitter.com/N023IyDGBi — Victoria Brownworth (@VABVOX) September 6, 2016



Others mocked Trump, claiming he is the least presidential-looking candidate of the two contenders.

"She doesn't even look presidential to me. She certainly doesn't," the dark spray tanned man with weird hair says of Clinton. — Sarah Reese Jones (@PoliticusSarah) August 27, 2016

Hahahahaha



Trump just said Clinton doesn't 'look Presidential."



It's like we're living in opposite land. pic.twitter.com/ioo2at46Sd — Sue 🌊 (@homenotalone) August 27, 2016



Republican National Committee spokesman Sean Spicer defended Trump on Tuesday, claiming a double standard exists in the media's coverage of the candidates' attacks against each other.

"Oh my God. Give me a break. I mean, at some point she can lob a million insults at Donald Trump and no one asks a question," Spicer said of Clinton during an interview with CNN.

"He says she doesn't appear to be presidential because of the actions that she's undertaken," he added. "It is about how she carries herself."