Sen. Bernie Sanders mocked President Donald Trump's tweet Saturday that urged people to have their own rally, which would be the "biggest of them all." The Vermont senator remarked, "They did. It wasn't," along with photos from Trump's Inauguration Day.

In his tweet, Sanders also posted pictures of the National Mall in Washington, D.C., on Trump's Inauguration Day to photos from the D.C. Women's March that took place the next day.

Trump has not responded to Sander's tweet yet. However, earlier his administration denied the media's portrayal of the inauguration that reported more people attended former President Barack Obama's inauguration in 2008 than those at Trump's.

Organizers said the Women's March drew 500,000 in Washington, D.C., and millions across the country, which was more than that on the president's Inauguration Day, according to the Washington Post. But, the fact-checkers in Trump's administration disapproved of these claims.

"This was the largest audience to ever witness an inauguration, period — both in person and around the globe," Press Secretary Sean Spicer said, during the White House news briefing last month. "These attempts to lessen the enthusiasm of the inauguration are shameful and wrong," he added, according to New York Daily News.

Speaking Friday at Conservative Political Action Conference in Washington, Trump said: "This place is packed, there are lines that go back six blocks and I tell you that because you won't read about it, okay. But there are lines that go back six blocks, there is such love in this country for everything we stand for, you saw that on Election Day."

However, according to several social media posts and other news reports, Trump's remarks were not exactly in line with what the photos showed.

Sanders had been critical of Trump since the presidential elections. "Our job is to do two things - to defeat Donald Trump and to elect Hillary Clinton. It is easy to boo, but it is harder to look your kids in the face if we are living under a Trump presidency," Sanders said in July at the Democratic National Convention in Philadelphia.

He had also called Trump a "pathological liar" and "fraud."

"We have a president who is delusional in many respects, a pathological liar," Sanders said on NBC's "Meet the Press" earlier this month. "I know it sounds — it is very harsh. But I think that's the truth. When somebody goes before you and says that 3 to 5 million people voted illegally… nobody believes that. There is not a scintilla of evidence to believe that, what would you call that remark? It's a lie. It's a delusion," he added.