Political science professor Kang Won-taek said high-speed communication in the world's most wired country has allowed the anti-government message to reach wide sections of society.
"Thanks to the Internet, this has become a voluntary participation by the people that just kept evolving," Kang said.
The protests started April against a beef deal with the United States that was meant to help a separate bilateral free-trade accord. U.S. lawmakers threatened to block the pact unless South Korea opened up its market to beef imports.
But widespread South Korean concern over mad-cow disease in U.S. beef quickly turned the issue into a lightning rod for a broad range of grievances against Lee's government.
U.S. and South Korean officials have said the beef is safe but that has done little to change minds in South Korea.
The issue threatens to overshadow a visit in about a month by U.S. President George W. Bush to Seoul for talks with one of his country's major trade and military allies in Asia.
Lee's cabinet offered to resign on Tuesday to take responsibility for the fallout from the beef deal.
It has been a dizzying reversal of fortune for Lee whose margin of victory was the biggest since South Korea began open presidential elections about 20 years ago, but who now has a support rate of under 20 percent.
Helping drag it down has been increasing gloom over the fate of Asia's fourth largest economy, which Lee came to office promising to boost but who is now warning that it faces a crisis due to the soaring international prices for raw materials.
Finance Minister Kang Man-soo said that a slump in domestic demand appeared to be deepening because of high inflation.
Local media said Lee would start a government reshuffle this week and speculated he would ditch his farm, health and education ministers, along with several aides, and possibly the foreign and finance ministers.
The growing political storm has all but blocked the government's plans for major economic reform, including tax cuts, privatisation of major state-run firms and banks and efforts to make the country more accessible to foreign investment.
Truckers, who voted to strike earlier this week over high fuel prices, have stopped work in various parts of the country, dragging down transport in the export-dependent country. More labour groups might follow, which could slow production for cars and other goods.
