Final answer:
The Democratic Party was responsible for first proposing old age and widows' pension, with the Social Security system being established under Democrat Franklin D. Roosevelt. The Second Party System consisted of the Democrats and Whigs, with the former supporting social welfare initiatives such as pensions.
Step-by-step explanation:
The political party responsible for first proposing the idea of old age and widows' pension in the United States is typically associated with the Democratic Party. The concept of social insurance for the elderly became a part of the Democratic Party's agenda during the 20th century, culminating in the establishment of the Social Security system under President Franklin D. Roosevelt, a Democrat, as part of the New Deal legislation. While there were social reformers and other smaller political groups, such as the Socialists, who advocated for social welfare programs earlier, the Democrats were the first major party to actually implement such a system on a national scale.
The Second Party System consisted of the Democrats and the Whigs. The Democrats were known for their support among the South, cities, farmers, artisans, and immigrants, while the Whigs typically drew their support from former Federalists, the North, the middle class, and native-born Americans. The Whigs, in contrast to the Democrats, dissolved in the early 1850s due to internal conflicts over the issue of slavery's expansion.