catalan independence spain
© ReutersCatalan pro-independence supporters hold a giant "estelada" (Catalan separatist flag) during a demonstration in Barcelona, Spain, Sept. 11, 2015.
The demonstration was held on the Catalan national day holiday, which marks the beginning of campaigning for regional elections.

Members of Catalonia's independence movement gathered in Barcelona, the regional capital, Friday, for a mass rally in support of a break with Spain. Hundreds of thousands of supporters filled the streets.

Friday's demonstration was held on the Diada, a Catalan national day holiday, which marks the beginning of campaigning for regional elections, seen by voters as a referendum on independence from Spain. The parties supporting independence need to secure at least 68 seats in the 135-member regional parliament to gain a majority, and polls suggest that they could achieve that in the Sept. 27 regional election.

Catalan regional President Artur Mas called snap regional elections in a bid to force the issue. Meanwhile, the government in Madrid has made clear again that it will not tolerate any such move. Prime Minister Mariano Rajoy has also stated that "there will be no independence for Catalonia."

Most polls predict that millions of Catalan will vote Yes, and, if that happens, the regional government will immediately begin preparations for secession in order to declare independence unilaterally as early as next year. If Catalans are successful, their victory could pave the way for other independence movements.

Catalonia is one of the wealthiest regions of Spain, making up nearly one fifth of the struggling Spanish economy. Spain's economic downturn, along with austerity policies and political scandals, have contributed to the renewed interest in independence.