MADRID: The global far-right is "unravelling", Spain's Prime Minister Pedro Sanchez said Wednesday as he celebrated the Democrat victory in US elections which saw them seize control of Congress in a rebuke to President Donald Trump.

"It happened in Brazil. It just happened in the US. And it will soon happen in Spain," said Sanchez, a global progressive star but whose premiership is in peril in snap elections he called for Nov 29.

The far-right wave of his rivals is "no longer growing, it is unravelling," he added.

The decisive victory by Democrats, who took both the Senate and the House of Representatives as well as a string of wins in deep Republican strongholds across the country, came days after the unexpected reelection of leftist Luis Inacio Lula da Silva as Brazil's president.