The liberal Ciudadanos came close to pipping the PP to second place, with 58 seats.
Vox came from a result of 0.2 per cent in 2016 to win 10 per cent, but it had the effect of cannibalising the Right-of-centre vote and helping Mr Sánchez to stretch out his lead. Together, the PP, Ciudadanos and Vox won 43 per cent, one point more than PSOE and Podemos combined.
The PP, Ciudadanos were hoping to combine with Vox for a majority to eject Mr Sánchez from power in order to crack down on Catalonia’s separatist leaders by suspending the region’s autonomy.
The three parties had accused Mr Sánchez of being a danger to Spanish unity after he used his 10-month-long spell in government before the election to seek a negotiated end to the impasse between Madrid and Catalonia’s regional government.
But Vox’s secretary general, Javier Ortega, was exultant over the result. “This is just the beginning,” he told supporters in Madrid’s Margaret Thatcher square. “Every Vox member of Congress is going to be a whirlwind.”