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MADRID (Reuters) - Spain’s liberal newcomer party Ciudadanos (“Citizens”) agreed on Sunday to back acting Prime Minister Mariano Rajoy in a confidence vote, but the support is not enough to end an eight-month political stalemate.

Rajoy’s centre-right People’s Party (PP) won most votes in two inconclusive general elections in December and June but it fell well short of a majority, leading to months of fruitless political negotiations to form a coalition.

Ciudadanos, which came fourth in both elections, said on Sunday it would add its 32 parliamentary seats to Rajoy’s 137 in Wednesday’s vote, but this still falls short of the 176 needed for an absolute majority.

The PP is also expected to get the backing of the small conservative Canary Island party Canarian Coalition, which will bring the support to 170 seats.

“We have managed to reach agreement amongst 170 seats so that Spain can have a government. It’s a large figure but it’s not enough,” Rajoy told a news conference where he called on other parties to end the deadlock.

Rajoy needs the abstention of the opposition Socialists to form a government, but they have steadfastly refused to smooth the way for an administration led by their main rivals.

To secure its backing, Ciudadanos demanded the PP agree to a list of conditions including the implementation of anti-corruption measures and an electoral reform to end discrimination in the voting system against smaller parties.

If Rajoy loses Wednesday’s vote, a second vote will take place on Friday where a simple majority will suffice to allow him to form a government.

If he loses this second vote, also likely without the support of the Socialists, it would trigger a two-month window to form a government at the end of which another election would have to be called, possibly on Christmas Day.