The Center Cannot Hold brought up a few historical themes that drove me to research a little more.
There is a line in the book that says a filibuster tied up old-age insurance. Below is what happened.
Social Security from ssa.gov
1923 Old-age assistance laws were passed in Pennsylvania and Nevada. They were later declared unconstitutional.
January 1, 1930 The California Old-age Pension Law, which was mandatory and Statewide in its application, became effective.
June 1, 1930 The Wyoming Old-age Pension Law became effective.
May 18, 1933 The first significant use of the term "Social Security" came about when the American Association for Old-age Security became the American Association for Social Security.January 17, 1935 The Committee on Economic Security's recommendations, embodied in the Economic Security Bill, were introduced in the 74th Congress. Recommendations included Federal old-age insurance, Federal-State public assistance and unemployment insurance programs, and extension of public health, maternal and child health, services for crippled children and child welfare services, and vocational rehabilitation but not health insurance. S.1130 was introduced in the Senate by Senator Robert F. Wagner; H.R. 4120 was introduced in the House of Representatives by Representative Robert L. Doughton; and H.R. 4142 was introduced by Representative David J. Lewis.
March 1, 1935 Congressman Frank Buck (Calif.) made the motion to change the name of the Economic Security Bill to the Social Security Bill. The motion was carried by a voice vote from the House Ways and Means Committee.
April 4, 1935 The Social Security Bill was introduced in the House of Representatives with a report. This bill (H.R. 7260) replaced the Economic Security Bill.
April 19, 1935 The Social Security Bill (H.R. 7260) was passed by the House of Representatives, 372 to 33 (25 not voting). Against were 13 Democrats, 18 Republicans and 2 Farm Labor.
May 13, 1935 The Social Security Bill (H.R. 7260) was reported out by the Senate Finance Committee with amendments, by a vote of 7 to 6. (Against, were 5 Republicans, 1 Democrat and there were 12 who did not vote.)
June 19, 1935 The Social Security Bill was passed in the Senate by a vote of 77 Yes, 6 No, and 12 Not Voting.
August 9, 1935 The Social Security Bill (H.R. 7260) was sent to the President after acceptance of the final conference report by the House and the Senate.
August 14, 1935 The Social Security Act (H.R. 7260, Public Law No. 271, 74th Congress) became law with the President's signature at approximately 3:30 p.m. on a Wednesday.
Filibuster (courtesy Brookings Institution)
1789 House and Senate rulebooks empower a simple majority to cut off debate.
1805 Aaron Burr suggests that they get rid of that rule so they do, which creates the possibility for a filibuster.
1837 First filibuster occurs, and few follow before the Civil War.
By the 1880s filibusters were more common and reform attempts were made.
1917 Adoption of Cloture--supermajority
I am pretty sure that Harry Turtledove mentions filibuster in "The Center Cannot Hold" because of Huey Long's June 12, 1935 filibuster.
There were more I researched, but I won't mention them here.
Sadly, I don't remember much about the characters except the hated Featherstone is President. I think I stopped reading the series because it reminded me too much of Trump. I'll pick it up later.