Anti-government demonstrators have fought running battles with police in Bolivia's main city, La Paz, despite the president's offer to resign.
The city echoed to the sound of dynamite blasts
Indigenous peasant farmers and labour activists played cat and mouse with the security forces, trading dynamite charges with police firing tear gas.
La Paz is cut off from the rest of the country as protesters demand energy nationalisation and political reforms.
Parliament has still to decide on a successor for President Carlos Mesa.
The demonstrators now want assurances that he will not be replaced by Congress speaker Hormando Vaca Diez, as the constitution dictates.
Mr Vaca Diez is widely loathed by the demonstrators, and analysts believe the only solution is for him to step aside and let the presidency pass to the head of the Supreme Court.
He would then be obliged to call fresh presidential elections, probably before the end of the year.
The BBC's Elliott Gotkine reports from La Paz that if Mr Mesa thought his offer to resign was going to pacify the protestors, he was wrong.
Some protesters tried to kick away police gas canisters
If anything, they have grown more violent and the place now feels like it is a city at war, our correspondent says.
Throughout Tuesday, poor Indian peasant farmers, miners and trades union members clashed with the police.
When they hurled deafening charges of dynamite, riot police responded with tear gas, forcing demonstrators and unlucky civilians to scurry for cover.
An Associated Press news agency correspondent says he saw at least three ambulances taking people away, and police making arrests.
The road blockades across Bolivia are strangling the country, with access to many of its neighbours now impossible.
In La Paz, prices on some products like meat have tripled, and rubbish is not being collected because lorries have no fuel.
Mr Mesa, who came to power 19 months ago after his predecessor was forced out by popular protests, announced his resignation in a televised address on Monday after a day of mass protests.
"This is as far as I can go," he said.
Mr Mesa offered to quit during similar protests in March, but the offer was rejected by Congress.
He has already discussed the possibility of a snap election with Church leaders and politicians.
The protests erupted last month after a law was passed imposing taxes on foreign companies that have invested in Bolivia's gas reserves, which are the second-largest in South America.
The protesters said the law did not go far enough and called for the gas industry to be nationalised.
They also want constitutional reforms to give greater rights to the country's impoverished highlanders, most of whom are of indigenous descent.
They oppose demands from Bolivia's resource-rich eastern provinces for greater autonomy and more foreign investment.