(Bloomberg) -- Thousands of Catalan secessionists marched in downtown Madrid to protest a trial of their leaders, stoking a political crisis that’s helped topple two Spanish government in less than a year.

In the biggest show of Catalan strength in the capital since the secession movement began gaining traction in 2012, marchers took to the iconic Paseo del Prado boulevard on Saturday with the motto “Self determination is not a crime -- democracy is to decide.”

The trial of 12 Catalan leaders for their role in a botched independence proclamation of 2017 is a central element in an election set for April 28. Prime Minister Pedro Sanchez dissolved his government in February and called an early election after pro-independence lawmakers who had backed his election last June withdrew their support to him as the trial started.

Sanchez was elected after his conservative predecessor Mariano Rajoy lost a confidence vote in parliament.

Polls suggest Sanchez’s Socialists would win the most seats in an election but fall short of a majority, meaning Sanchez may depend again on the Catalans to govern. The separatists have demanded that the government should help stop the trial and back their plea for an independence referendum.

Demonstrators arrived mainly in some 380 buses or by train from Barcelona, about 500 kilometers (310 miles) to the east. Marchers included Catalan President Joaquim Torra, one of his predecessors, Artur Mas, and lawmakers from the region.

Organizers put the crowd size at an estimated 120,000. Spanish police counted about 18,000.

To contact the reporter on this story: Rodrigo Orihuela in Madrid at rorihuela@bloomberg.net

To contact the editors responsible for this story: Charles Penty at cpenty@bloomberg.net, Tony Czuczka, Virginia Van Natta

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