Complex sentence: This was a surprising move, after strongly attacking PSD in the June partial elections, however it ensured that the PUR would be able to enter the parliament on the coattails of the much larger party.
Split into simpler sentences: This was a surprising move, as the PUR had strongly attacked the PSD in the June local elections. However, it ensured that the PUR would be able to enter the parliament on the coattails of the much larger party.