Occupy DC protesters defied a threatened police clampdown on their tent colony Monday, pitching a massive "tent of dreams" in the park near the White House they took over four months ago.

With several hundred cheering supporters looking on, but no police in sight, they hoisted a deep-blue tarpaulin over an equestrian statue of Civil War general James McPherson in the downtown Washington square that bears his name.

Under the tarp, and surrounding the granite base of the statue, were about 18 smaller tents and pet igloos, as well as sleeping bags, signaling Occupy DC's intention to stay put and defy the National Park Service camping ban.

"This is what democracy looks like!" the festive crowd chanted under clear blue skies, as they took turns denouncing income inequality, bank bailouts, corporate influence on politics, student debt and war.

On the edge of the tarpaulin painted with dreamy crescent moons and shooting stars, a theme-setting poster read: "Let us sleep so we can dream."

"Their time is up," shouted one masked protester, referring to the US corporate and political establishment. "They just don't know it yet. They're paper tigers and we are a scorching fire."

The National Park Service, which owns and polices the square, and under pressure from Republican congressmen, said Friday it would begin applying its ban on camping on park land from noon (1700 GMT) Monday.

Park Police spokesman Sergeant David Schlosser told reporters Monday that officers "will take a measured and appropriate response" to the protesters -- but he stopped short of saying when they would intervene.

Online, nearly 19,000 people signed a "leave Occupy DC alone" petition on the boldprogressive.com website. It argued that First Amendment rights to free speech trump no-camping rules.

Since Occupy DC pitched camp on October 1 on the heels of Occupy Wall Street in New York, its presence has been tolerated by the National Park Service as a "24-hour vigil" despite a chorus of complaints from local businesses.

The park service changed tack after its director Jonathan Jarvis came under intense grilling from Republicans on the House of Representatives oversight committee who demanded to know why it was not enforcing its own rules.

White House spokesman Jay Carney said Monday: "Our position has been, and continues to be, that we need to balance First Amendment concerns -- the right to demonstrate, the right to speak freely and -- with public safety concerns and public health concerns."

Tension on McPherson Square flared anew Sunday when Park Police officers used a Taser at point-blank range to disable a protester, Ryan Lash, who allegedly interfered with their distribution of no-camping flyers.

The ban on camping and overnight sleeping also applies to a separate protest called Occupy Washington DC, at nearby Freedom Plaza, where some participants told AFP they would comply without quitting the venue altogether.

Inspired in part by the Arab Spring, the Occupy movement erupted across the United States in September and October, taking over public spaces in several cities. The original New York encampment near Wall Street was shut down by police in November.

Over the weekend, in the most violent Occupy protest this year, police in Oakland, California fired tear gas and arrested more than 400 people as local Occupy protesters tried to take over City Hall and other buildings.