Demonstrators chanted "Ah-Bian, step down!" as they marched through the centre of Taipei on Saturday, many clad in red to express their anger with Taiwan’s leader, Chen Shui-bian.
The protest was organised by Shih Ming-teh, a former ally of Chen ally who has collected more than one million signatures in a petition to force him out and who has vowed a round-the-clock sit-in outside Chen's office until he resigns.
On the eve of the rally, Shih said he was expecting 300,000 people to take part in an event that he said would mark "a new page in history" and "topple a corrupted leader" who has been dogged by repeated allegations of wrongdoing.
"Ah-Bian has failed to give a convincing explanation regarding the several corruption cases," said one demonstrator, Chou Yi-chu, who had gone to the rally with his wife and three-month-old daughter.
Chen’s troubles began in May after his son-in-law Chao Chien-ming was detained and later indicted on suspicion of insider trading and taking bribes. Chen has publicly apologised for Chao's actions.
His problems were compounded when prosecutors began investigating last month whether he had misused funds intended for national affairs.
Chen has repeatedly denied any wrongdoing and vowed to finish out his term.
Reports in the Taiwanese media have alleged that prosecutors found only half of the funds for which Chen's office had declared receipts and suspected that some of the money might have been used illegally.
Protestors went to some lengths
to show their disapproval
In June a vote designed to provoke a national referendum on Chen’s future failed to gain the necessary approval of two-thirds of parliament.
Furthermore his wife, Wu Shu-chen, is also under investigation for allegedly accepting department store gift certificates in exchange for lobbying efforts.
But despite a petition signed by more than one million people and three million dollars in financial backing, analysts say Chen is unlikely to be forced to resign just yet.
Up to 4,600 riot police were deployed on Saturday to prevent any violence and around 600 barbed-wire barricades were set up, according to Wang Yung-hui, deputy chief of the Taipei police department.
On Friday some 2,000 Chen supporters rallied outside his office while in southern Taiwan in one of several pro-Chen rallies held ahead of Saturday's protest.
Taiwan split from mainland China in 1949 and is regarded by Beijing as a renegade province. It had been governed for more than half a century by the nationalist Kuomintang (KMT) until Chen was elected in 2000.