Washington, DC - A former US Olympian who faces up to 10 years in prison for alleged vandalism of Washington's newly resurfaced – but already peeling – Reflecting Pool pleaded not guilty Thursday as supporters rallied outside the court.

Dozens of people carrying placards with slogans like "Scapegoat!" and "Trump blames everyone but himself" gathered for the first hearing in a case that intensified concerns over a politicized justice system under President Donald Trump.

David Hearn (67) pleaded not guilty at the District of Columbia Superior Court following his felony indictment for allegedly causing more than $1,000 in damage to the pool, which forms part of the Lincoln Memorial.

The over-$14 million renovation, one of Trump's pet projects to remake the US capital, has been dogged by the rapid regrowth of algae and peeling paint.

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"If Mr. Hearn can be charged with a felony for touching the Reflecting Pool, every American is at risk," one of Hearn's attorneys, Norm Eisen, told reporters outside the court.

"This indictment reflects the administration's effort to scapegoat Davey and to shift blame for their own failures."

Standing alongside the attorney, Hearn – a three-time Olympic canoeist – did not speak but pumped his fist as he departed, with supporters chanting his name.

In the indictment filed last week, prosecutors alleged that on June 19, National Park Service employees observed Hearn "forcefully and violently pulling up and removing" approximately two square feet of paint from the base of the pool.

Hearn has told the media that when he visited the pool, he noticed a piece of partially detached "American blue" paint liner. He reached into the water to see what it felt like, and as he prepared to leave, US Park Police arrested him.

The US attorney for the capital, former Fox News host Jeanine Pirro, has vowed to hold to account anyone who damages national monuments and said her office is reviewing about a half-dozen other cases related to the pool, which will be misdemeanors or violations.

The Reflecting Pool is one of several beautification projects in Washington as the US marks 250 years since independence.