Complex sentence: One of the components of the new party was the little Social Democrats, who in turn had started as a splinter party of the Pensioners Party, and the Democrats originally tried to take advantage of this party's status to run for election.
Split into simpler sentences: One of the components of the new party was the minor Social Democrats, which in turn had been formed as a splinter party of the Pensioners Party. The Democrats originally tried to take advantage of this party's status to run for election.