Over 5,000 protesters marched through the financial district here on Monday, denouncing the administration of President Gloria Macapagal Arroyo and moves to amend the country's Constitution.
The demonstrators, including leftist activists, workers and students, marched along Ayala Avenue in Makati City at the height of morning traffic.
They demanded Arroyo's resignation and denounced the charter change (known as cha-cha) campaign of her allies in the House of Representatives despite assurances that the move was already abandoned.
They carried placards and banners reading, "Junk Cha-Cha", "Oust Gloria" and "Resign All, Government for the Masses."
The demonstration came a day after over 30,000 people joined a prayer rally in the Rizal Park here protesting efforts by Arroyo and her allies to amend the country's 19-year-old constitution.
The crowd turnout at Sunday's rally was below the expected half a million, amid warnings by government security officials that "communist provocateurs" might disrupt the gathering.
The Roman Catholic Church, which organised the prayer rally, said the warnings scared a lot of would-be participants.
During the rally, the Church called for character change instead of charter change, especially among the country's political leaders.
Monsignor Pedro Quitorio, spokesperson for the Catholic Bishops Conference of the Philippines (CBCP), said the church plans to launch a nationwide campaign of "political education".
He said the campaign aims to teach Filipinos how to vote wisely in the May 2007 congressional elections.
"Filipinos don't realise that their votes have great consequence," he said. "We must learn to vote for people who can bring about positive change, not to vote in exchange for traditional patronage."
Arroyo has been pushing for constitutional amendments to shift the current presidential, bicameral form of government to a parliamentary, unicameral system.
But many Filipinos do not support the proposals, believing that the move only aims to extend the terms in office of elected officials, including many of Arroyo's allies.