MADRID — Spain’s leading opposition Socialist party was in crisis Thursday, a day after nearly half of its executive board resigned in a rebellion against leader Pedro Sanchez.

The schism comes as Spain is about to enter its 10th month without a fully functioning government following two inconclusive elections in December and June.

Critics of Sanchez blame him for the Socialists’ worst results ever in the elections. They also say his insistence on blocking attempts by acting Prime Minister Mariano Rajoy to form a minority government and end the political impasse is damaging the country.

Sanchez met Thursday with the remainder of the board, which announced it would press ahead with a federal committee session Saturday to propose a leadership election Oct. 23 in what is seen as a clear challenge to his critics. The board called for calm during what it described as “unprecedented moments” for the 137-year-old party.

It was not clear whether Sanchez’ opponents will boycott the meeting or try some other action beforehand to oust him.

The revolt should, in theory, benefit Rajoy but the Popular Party leader has yet to say whether he will try again to win parliament’s backing after being voted down twice a month ago.

Parliament has until Oct. 31 to form a government or the country will face an unprecedented third election in a year.

The Socialists, who have run most Spanish governments since democracy returned in 1978, won just 85 seats in the 350-seat parliament in the June election, the fewest ever.

Wednesday’s revolt came after party heavyweight and former Socialist Prime Minister Felipe Gonzalez said he felt cheated because Sanchez had told him he would abstain in the Rajoy vote and let the conservative leader form a government. But Sanchez and his lawmakers opposed Rajoy in the two votes.

Rajoy has been heading a caretaker government. His party won the most seats in both elections, but still lacked a handful of votes or abstentions in Parliament to form a government.