MADRID, Aug 4 (Reuters) - A new leftist party has become Spain's third most popular political force, a poll showed on Monday, tapping into discontent with the two mainstream parties after corruption scandals and austerity measures in an economic slump.
Podemos (We Can) took a surprise 8 percent of the vote in Spain's European Elections in May to win five seats and would gain 15.8 percent of votes in a parliamentary election, the state-sponsored poll by the Centre for Sociological Research (CIS) showed.
The ruling People's Party (PP), seen as a beneficiary of a nascent economic recovery, would win 30 percent of votes while the Socialists would gain 21.2 percent, CIS forecast.
That puts Podemos, headed by political science lecturer Pablo Iglesias, ahead of United Left, which the poll saw gaining 8.2 percent of the vote, and centre-left UPD with 5.9 percent.
The next parliamentary election is due in late 2015.
(Reporting By Inmaculada Sanz; Writing by Sarah Morris; Editing by Janet Lawrence)