Complex sentence: A failed mayoral bid in 1951 marked the end of his serious political career, although he continued to support other candidates and remain active within the Democratic Party, and even ran for mayor one last time in 1955, his 10th time running for the office.
Split into simpler sentences: A failed mayoral bid in 1951 marked the end of his serious political career, although he continued to support other candidates and remained active within the Democratic Party. He ran for mayor one last time in 1955, his 10th time running for the office.