Thousands of Spaniards answered a call on Saturday from far-right party Vox to protest against lockdown measures and the increasingly beleaguered government of leftist Pedro Sanchez.
Motorists thronged the roads of central Madrid, tooting their horns as others held placards and shouted "Sanchez, resign" and "freedom".
Vox called demonstrations in dozens of cities with its leader Santiago Abascal alleging the government "has been incapable of protecting its people, its elderly and its careworkers" during the coronavirus crisis.
The pandemic has killed 28,600 in Spain to date, one of the world's highest tolls.
"I came as I believe the government of Pedro Sanchez has lied to us," said protester, Marina Samber, 51, clad in a green mask - Vox's colour.
"He played with the health of elderly people as he didn't provide us with masks or security measures to prevent contamination."
The crisis has turned up the heat on Sanchez - crowds in several cities banged pots and pans in protest on Friday, accusing his team of mismanaging the virus response and shrinking civil liberties through one of Europe's toughest lockdowns.
A vote to extend a state of emergency to June 6 passed by just 15 votes this week after frenetic horse-trading, as the government pursues a staggered exit from lockdown through to the end of June.
One of the protesters, Oscar de Lolmo, a 51-year-old engineer sporting a watch decorated with the Spanish flag, said he believed "the government is going to plunge us into an economic crisis".
Others likewise bitterly attacked Sanchez.
Government ministers were "the assassins of 40,000 people", claimed Carlos De Lara, insisting the true death toll is much higher than officials say.
Others complained at the continuing general lockdown in large cities such as Madrid and Barcelona, which will start being rolled back from Monday after 10 weeks.
"Small and medium-sized firms are sinking," said Ignacio Gonzalez, a 23-year-old engineering student.