BARCELONA, Spain — Hundreds of thousands of pro-independence Catalans took over downtown Barcelona and four other cities on Sunday to urge their politicians to push ahead with plans to break away from the rest of Spain.

For a fifth consecutive year, demonstrators used Catalonia’s national day to raise the secessionist pressure on politicians in Madrid. But unlike protests in previous years, the demonstration took place amid a serious political deadlock in Spain, which has been without an elected government since inconclusive elections last year. Another general election, the third in a year, is likely to be held in December.

Sunday’s protest in Barcelona was smaller than ones in the past, with a turnout of 540,000 people, according to the local police. In 2012, when the first such giant demonstration was held, 1.5 million people took part, according to police estimates.

But comparisons were difficult to draw, because the organizers decided this year to add demonstrations in four other cities in Catalonia, which is home to 7.5 million people, rather than have all the protesters converge on Barcelona.