European Union Monetary Affairs Commissioner Mr Pedro Solbes has accepted an offer to return to Spain as economy minister and deputy prime minister in the new Socialist government.
Mr Solbes's decision means he will have to step down early from the European Commission, where he gained a reputation as a staunch defender of the budget rules underpinning the euro.
Mr Solbes told reporters in Brussels late last night he had been planning to stay in the EU job until the current European Commission's term ends in October.
But incoming Prime Minister Jose Luis Rodriguez Zapatero, who scored an upset win in Spain's March 14th general elections, had offered him a position in the new government and he had accepted, he said.
"I think that the challenge is very important and we'll see what we can all do together," Mr Solbes added.
A Socialist Party statement issued in Madrid said Mr Solbes would become both second deputy prime minister and head of a unified economy and treasury ministry. The ministries had been split into two under the outgoing Popular Party government.
The return of Mr Solbes, who served as economy minister under a previous Socialist government, gives weight to Mr Zapatero's government, which is expected to take office in late April.