Update the latest News: Thai protesters collect blood for message
Thousands of "red shirts" hold out forearms to give blood for message
Demonstrators threaten to to splash blood on ruling party headquarters, PM's residence
Protesters are supporters of ousted Prime Minister Thaksin Shinawatra
Bangkok, Thailand (By: CNN) -- Anti-government protesters launched a blood drive Tuesday to collect enough samples to douse the ministers' offices.
The dramatic gesture is the latest move by the anti-government United Front for Democracy Against Dictatorship (UDD) to force Prime Minister Abhisit Vejjajiva to dissolve parliament and call new elections.
Thousands of "red shirts" -- so named for their clothing -- held out their forearms to allow their compatriots to draw blood.
The protesters intended to collect 1,000 liters (1 million cubic centimeters) and then throw the blood on the grounds of the Government House, which houses ministerial offices, at 6 p.m. (7 a.m. ET).
The anti-government demonstrations began Friday. By Sunday, tens of thousands of protesters had poured into the center of Bangkok.
The rallies have been largely peaceful. Abhisit has said his government will not use force to quell the demonstrations.
The nation's tourism minister estimated the demonstrations might have resulted in a 20 percent drop in tourists. The impact on Chinese visitors appears to have been greater, with the Chinese Chamber of Commerce reporting a 50 percent cancellation rate.
The protesters are supporters of former Prime MinisterThaksin Shinawatra, who was ousted in a bloodless military coup in 2006.
Thaksin was the only Thai prime minister to serve a full term and remains hugely popular.
He fled the country in 2008 while facing trial on corruption charges that he says were politically motivated.
The protesters say Abhisit was not democratically elected and have demanded that he call new elections.
Since Thaksin's ouster, Thailand has endured widespread politicalunrest that has pitted Thaksin loyalists against Abhisit supporters.
Two people were killed and at least 135 wounded in riots in April 2009 when protesters clashed with demonstrators supporting the government.
CNN's Kocha Olarn and Dan Rivers contributed to this report