t was a protest being invented and reinvented throughout the day, veering from the humorous and the peaceful to the confrontational and defiant.
The daylong series of protests against the presidential debate format and the two major candidates started with puppet theater on Boston Common and ended with a human blockade outside the University of Massachusetts at Boston, with people throwing rocks at police, spitting on police cars, and at one point ripping a windshield wiper off a police van and hurling it at officers.
Tensions were palpable between those who wanted to offer a low-key, alternative platform - with street theater, small discussion groups, and even dancing - and those who wanted to storm barricades and disrupt the event.
In the end, both forms of protest unfolded. For 45 minutes, several hundred Ralph Nader supporters who sat in the streets and linked arms were able to prevent buses from picking up those who attended the debate. The buses eventually picked up guests at another exit.
Even amidst the protests, it was common to find people arguing over strategy. As events became more violent, one man was kicking and spitting on a police cruiser. A woman pulled him away and said, ''What are you doing? We're supposed to be peaceful.''
Another young man, with a bandanna across his face and black clothes, was overheard discussing some form of violence or confrontation. Two others tried to dissuade him.
''Let the violence be on their heads,'' a woman told the young man. ''They are looking for reasons to discredit us.''
The night started a little more calmly. Thousands of people marched down Morrissey Boulevard toward the debate site from separate rallies, one in South Boston calling for inclusion of more candidates, one in Dudley Square against the death penalty.
Some came to support Palestinians in the wake of this week's violence in Jerusalem. Others supported the Libertarian Party. There were people demanding freedom for Pennsylvania death-row inmate Mumia Abu-Jamal, and those supporting jailed Native American Leonard Peltier, among many other groups and causes.
Those from numerous groups calling for a wider range of candidates in the debate sat in a giant circle in the middle of the street, watching puppeteers perform skits about democracy. They stood to join in the dancing when performers started circling in the street, to the beat of drums, carrying giant birds on sticks.
One puppet show, called ''A Goat With a Vote,'' told the story of an 18-year-old goat who registers to vote and learns how to become an informed citizen.
Then about 60 people broke into small groups to discuss their concerns about capitalism, the environment, and other issues.
''This is just fantastic; it shows the level of discontent and disenfranchisement that people feel,'' said Jonathan Leavitt of the Massachusetts Green Party, toward the end of the night. ''This picture speaks volumes.''
In addition to protesters of the debates, thousands - mostly union members - came out to support Al Gore, among them several hundred Boston firefighters protesting a lack of a contract. Tensions ran high between Nader supporters and unions, with reports that some Gore demonstrators attacked the Nader protesters.
Protesters directed much ire at the Commission on Presidential Debates, which excludes candidates lacking 15 percent support in the polls. Jamin Raskin, an American University law professor who has pushed for Nader's participation, compared the commission to the Wizard of Oz, ''a great and mysterious power.''
''They are stealing your presidential election right before your very eyes,'' Raskin said.
If corporations and the commission were the bad guys, Nader was certainly the hero of the day for the majority of protesters.
Theresa Del Pozzo of St. Johnsbury, Vt., who came for the protests, pointed out that 12,000 people paid $10 to see Nader in Boston on Sunday. ''Just imagine how many more millions would like to hear him speak,'' she said.
Andy Dabilis, Patrick Healy, and Beth Daley of the Globe Staff contributed to this report.
