NEW YORK -?"Occupy Wall Street" protesters targeting US corporate greed are gaining both in numbers and influence, as the movement is entering its fourth week and keeps spreading from the financial district of New York City to other American cities, with no signs of dying down in the foreseeable future.

On Friday at Zuccotti Park, a privately-owned property near Wall Street where the movement activists have camped out since mid- September, hundreds of protesters arose from sleeping bags to a new day of more scheduled protesting events. A placard stands out with a slogan saying "We will Stay Until Change Happens."

"We are definitely not leaving," said Karin Gramalski, 38, while picking out some toothpaste and some lotion from what the protesters refer to as the "sanitation station," which supplies items from toilet paper to dental floss.

"We are gaining in number, not just here but across the country too," she added. "We have everything here, food, medical stuff, tech stuff, music, art. We will all stay as long as we need to."

The "Occupy Wall Street" protests emerged on September 17, with only a few dozen demonstrators -- mostly young people -- trying to erect tents before the New York Stock Exchange. With access denied by the police, they turned to Zuccotti Park as their camping ground. The number of participants has since grown to hundreds, with such facilities as food stand, mini-library and makeshift hospital set up on site. They even started to publish their own newspaper, ironically titled "The Occupied Wall Street Journal."

The protesters speak against corporate greed, social inequality, global climate change and other problems, but have so far failed to render any clear political demand or reform scheme. Nevertheless, they have found vehement support from people of various walks of life, as an increasing number of Americans are frustrated by the country's slow recovery from the three-year recession and persisting high unemployment of 9.1 percent.

While thousands of New York City union workers and university students took to the streets in downtown Manhattan on Wednesday to show their support to "Occupy Wall Street," the movement has also spread to other US cities including Chicago, Los Angeles, Washington DC and Boston.

Hundreds of protesters on Thursday afternoon converged in front of the US Chamber of Commerce in Washington DC, under a huge banner hanging overhead that read "JOBS." The protesters began their day at Freedom Plaza on Pennsylvania Avenue, tucked between the White House and the Capitol, and many camped out on the plaza.

Meanwhile, several hundred frustrated residents and homeowners marched in Los Angeles, California on Thursday to protest against big banks for "destroying jobs and neighborhoods with their greedy, reckless and predatory business practices." The protesters marched outside the offices of Wall Street banks, including Bank of America, Chase and Wells Fargo.

Also on Thursday, President Barack Obama broke his silence on the movement, telling a White House press conference that the anti- Wall Street protests were an expression of frustration over the financial sector by the American public.

"I have seen it on TV and I think it expresses the frustration that the American people feel," said Obama. "The protesters are giving voice to a more broad-based frustration about how our financial system works."

Scholars and experts hold different views on the movement's development trends and possible impact.

According to Professor Patrick Bolton of Columbia Business School, the "Occupy Wall Street" protesters seem to have been inspired by the examples of Egypt and the 15-M movement in Spain.

He believed the movement will be short-lived and could hardly impact the existing system: "If you look at what happened (in Spain), the movement just petered out, and now the focus is on the general elections."

But Jean Cohen, political science professor at Columbia University and John Dinges, journalism professor at Columbia University, disagreed. They predicted to Xinhua that the protests will have a long-term impact on policymakers and eventually force them to take right steps.