BARCELONA — Prosecession parties pushing for Spain’s northeastern Catalonia region to break away and form a new Mediterranean nation won a landmark vote Sunday by capturing a majority of seats in the regional Parliament, setting up a possible showdown over independence with the central government in Madrid.

With 98 percent of the vote counted, the ‘‘Together for Yes’’ group of secessionists had 62 seats in the 135-member Parliament. If they join forces with the left-wing proindependence Popular Unity Candidacy party, which won 10 seats, they will have more than the 68 seats needed to try to push forward their plan to make Catalonia independent from Spain by 2017.


But the Popular Unity Candidacy party had insisted that it would join an independence bid only if secessionist parties won more than 50 percent of the popular vote. They won only about 48 percent. A quirk in Spanish election law gives a higher proportion of legislative seats to rural areas with fewer voters. Still, Catalonia leader Artur Mas claimed victory, and David Fernandez, leader of the Popular Unity Candidacy party, said in a television interview that his party ‘‘will not be the one to fail independence.’’ But he has said he wants an immediate declaration of independence rather than the 18-month secession road map favored by the ‘‘Yes’’ bloc.

Associated Press