Complex sentence: Abzug's career in Congress ended with an unsuccessful bid for the Democratic nomination for the US Senate in 1976, when she narrowly lost to the much more conservative Daniel Patrick Moynihan, who went on to be elected and served four terms.
Split into simpler sentences: Abzug's career in Congress ended with an unsuccessful bid for the Democratic nomination for the US Senate in 1976. She was narrowly defeated by Democrat, Daniel Patrick Moynihan, who went on to be elected and served four terms.