Sen. Chris Van HollenChristopher (Chris) Van HollenProgressive tax-the-rich push gains momentum Senators pressure Trump to help end humanitarian crisis in Kashmir Democratic candidates are building momentum for a National Climate Bank MORE (D-Md.) swiped at President TrumpDonald John TrumpMarine unit in Florida reportedly pushing to hold annual ball at Trump property Giuliani clashes with CNN's Cuomo, calls him a 'sellout' and the 'enemy' Giuliani says 'of course' he asked Ukraine to look into Biden seconds after denying it MORE on Saturday while attending the "March for Our Lives" rally in Washington, D.C., calling for action on gun violence.

Asked about estimated attendance at the rally, which was expected to draw hundreds of thousands of people, Van Hollen told The Hill, "I can tell you for sure, it's larger than the Trump inauguration."

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While exact turnout figures have yet to be released, organizers obtained a permit for 500,000 people to rally in D.C. around Pennsylvania Avenue near the White House. Hundreds of similar marches were planned worldwide.

Trump sparked backlash last year after sending then-White House spokesman Sean SpicerSean Michael SpicerSpicer on 'Dancing with the Stars': 'Those of us who stand for #Christ won't be discounted' Spicer makes debut on 'Dancing With the Stars' to Spice Girls song Merriam-Webster: A 200-year-old dictionary offers hot political takes on Twitter MORE to confront members of the media over coverage of his inauguration crowd size after taking office.

Spicer claimed the press misrepresented the number of people at the inauguration after numerous reports indicated that the crowd was much smaller than former President Obama’s 2009 inauguration crowd.

The White House spokesman claimed at the time that Trump's inauguration crowd size was “the largest audience to ever witness an inauguration, period, both in person and around the globe,” garnering pushback from the media.

Spicer said in September that he regretted his fiery exchange with reporters.

— Mike Lillis contributed