They said President Arroyos hold on power has been growing more tenuous by the hour as various opposition groups demanded that she step down following allegations that she rigged last years election, and that her family accepted gambling payoffs.
Left-wing groups have been at the forefront of street protests demanding Arroyos resignation, as they were in the past two "people power" revolutions.
But even though the leftists formed the core of the uprisings that toppled the late dictator Ferdinand Marcos in 1986 and President Joseph Estrada in 2001, they were sidelined after both shut out of the governments of President Corazon Aquino, who followed Marcos, and the Arroyo administration that replaced Estrada.
This time, the demonstrations have only drawn a fraction of the massive crowds that swarmed the streets in those uprisings. Philippine leftists acknowledge their cause and their influence may be withering, despite their history of leadership in the popular revolts.
Ten left-wing lawmakers from various groups now have seats in the nations 236-member House of Representatives. Polls show about 27 percent of voters support left-wing groups. Communist guerrillas, believed to number about 8,000 fighters and considered a major security threat, have been weakened by battle setbacks, factionalism and dwindling support.
"We must unite and show the people we can get our acts together," said Ric Reyes, a former Communist Party Central Committee member and now chairman of Akbayan Citizens Action Party. "That is the first step in gaining credibility. A united left is more credible than a disunited one."
As the movement to remove Mrs. Arroyo gathers steam, the fragmented leftists seem to be finding some common political ground. The factions agree that merely removing Mrs. Arroyo, or replacing her with Vice President Noli de Castro, is unacceptable. They want a transition government installed to start fundamental reforms.
Francisco Nemenzo Jr., former president of the state-run University of the Philippines and head of the newly formed left-wing coalition Laban ng Masa, is one of the main proponents of a transition government.
"The crisis is not just a crisis of the presidency," Nemenzo said. "It is the crisis of the entire system of elite rule. Unless you change the system of elite rule, no amount of changes at the top will amount to anything." AP