At least 7,000 Latvians have rallied peacefully in the capital, Riga, to call for the government to step down and for action against corruption.
It was the second large protest in two weeks against a cabinet widely condemned for trying to dismiss the head of the anti-corruption agency.
Auditors recently detected financial irregularities in the agency.
But opposition figures say that was an excuse to stop it investigating people close to the prime minister.
The political crisis in Latvia has led to growing speculation that the coalition government could collapse.
Correspondents say Saturday's demonstration was one of biggest since Latvia gained independence from the USSR in 1991.
It is just over a year since Latvia's last parliamentary election in which Prime Minister Aigars Kalvitis won a historic second term.
Mr Kalvitis, who leads a centre-right coalition, suspended anti-corruption chief Aleksejs Loskutovs in late September in a move which took many by surprise.
Last week, he withdrew his decision but the government has lost three ministers in connection with the affair.
President Valdis Zatlers has called on the government to resign after a budget vote next week.
"The president believes that the government would be honest if it resigned as a whole after the acceptance of the state budget," a presidential spokeswoman said.
Mr Zatlers joined the rally on Saturday, urging demonstrators to abide by the constitution, the Associated Press news agency reports.
"We should not play with democracy," he said in a speech interrupted several times by demonstrators' calls to dissolve parliament.
The rally backed an appeal to the government to ensure the independence of the legal system and fight corruption, Reuters reports. ( BBC )