Tens of thousands of people took part in rallies throughout Bulgaria on Sunday to call for government steps to ease the level of poverty.
Prime Minister Boiko Borisov's cabinet was last week forced to resign and an early election is expected by May.
Much of the public anger is directed at power companies, whose bills at times exceed incomes. Average salaries in Bulgaria are 400 euros ($US530) per month and pensions are less than half that amount.
Over 10,000 people marched through downtown Sofia, waving Bulgarian flags and slogans reading "Fighting for decent life" and "Down with monopolies".
Demonstrations also took place in around 40 other cities, with about 15,000 people marching in Plovdiv and Varna, Bulgaria's second and third largest cities.
The protesters also called for changes to the constitution, to allow direct votes for parliamentary deputies, rather than party lists.