Deputy Prime Minister Alfredo Perez Rubalcaba said Friday that he will leave the government to focus on his role as standard-bearer of Spain's governing Socialists in the 2012 general elections.

"Though there is no legal incompatibility" between his continuing to serve as interior minister and deputy premier while seeking to lead the next government, it is time to concentrate on next year's balloting, he said at a press conference after the weekly Cabinet meeting.

He said he conveyed his decision to Prime Minister Jose Luis Rodriguez Zapatero, who announced in April that he would not run for a third four-year term.

Rubalcaba will be formally designated on Saturday to head the ticket of the Socialist Workers Party of Spain, or PSOE, in elections now scheduled for March 2012.

The main opposition conservative Popular Party, which leads in the opinion polls, has repeatedly demanded that Zapatero call early elections. Spanish media have speculated the voting could be moved up to this fall, but the prime minister has given no indication he plans to make such a move.

After insisting that it was up to Zapatero to decide the exact date of his departure from the administration, Rubalcaba said it could be "tomorrow, Sunday or in the first days of next week."

Beginning Saturday, Rubalcaba said, "I will be fully committed to my party."

The PSOE is eagerly looking forward to hearing the campaign platform Rubalcaba plans to outline on Saturday, Zapatero said this week.

The overriding issue in the 2012 contest is likely to be the economy, which is still struggling to surmount the effects of the global recession and the bursting of a massive real estate bubble, a task made more difficult by pressure from financial markets to curb the deficit.

Spain's unemployment rate stands at more than 21 percent and growth remains sluggish.

Rubalcaba is a PSOE veteran who served in the Cabinet during the 1982-1996 tenure of Prime Minister Felipe Gonzalez. His opponent in next year's contest, PP leader Mariano Rajoy, lost to Zapatero in 2004 and 2008.