Complex sentence: The Spanish Socialist Workers'Party found itself unable to gain any of the PP's lost support and lost votes too, to the benefit of until then minority parties such as United Left, Union, Progress and Democracy, Citizens or the newly created Podemos party.
Split into simpler sentences: The Spanish Socialist Workers'Party found itself unable to gain any of the PP's lost support and lost votes too. This erosion of support for the 2 traditional big parties of the Right and Left allowed until then minority parties such as United Left, Union, Progress and Democracy, Citizens or the newly created Podemos party.