BANGKOK — Blood was spilled on Tuesday, the third day of mass demonstrations in Bangkok, but not in the way that many had feared.

Antigovernment protesters pooled their blood — drawn by medical workers in air-conditioned tents — to unleash a red tide at the gates of Government House, the office of Prime Minister Abhisit Vejjajiva, and later at his party’s headquarters.

“We will curse them with our blood and our soul!” yelled a protest leader, Nattawut Saikua, to roaring approval from a crowd of several thousand people at Government House, including farmers, monks and vegetable sellers.

Their so-called Red Shirt protest movement remains resentful over the 2006 military coup that ousted former Prime Minister Thaksin Shinawatra, who championed rural and poorer voters. The movement accuses the current government of favoring the country’s wealthy elite, and has been angered by a series of court decisions in recent years banning political parties allied with Mr. Thaksin.