It's a Presidents' Day party! I guess this used to be the date set aside to celebrate Washington's birthday, but all of those annoying car dealership sales ads would be boring if it was only our first president involved. I am, however, somewhat tickled by the Washington Crossing the Delaware Turnpike advertisement for Geico.
Sorry, got carried away there. I count 15 clues directly related to Presidents or their designated holiday. I could expand that to 19 if you include 35A: Some rulings on PolitiFact (LIES), 51A: President pro ___ (TEM), 22D: What a majority of campaign spending goes toward (ADS), and 67D: Political connections (INS). It's one way to enliven necessary short answers.
Meanwhile, the main theme takes five Presidents' names, and anagrammatizes them with a single added letter to come up with a new word. Huh. It's clever, but honestly, only James Madison would qualify in anybody's book as a President worth celebrating among these five. Garfield was assassinated after only 200 days in office. Fillmore managed to get the Compromise of 1850 passed, and later ran as a member of the racist Know Nothing party. Harding's administration was plagued by more scandals than almost any president, including the Teapot Dome affair. And Coolidge was best known for what he didn't say ("Silent Cal").
The actual theme answers are all solid. It would have been extra cool if the extra letter added to each answer spelled something together, but perhaps that's asking too much, given the conceit.
Anyway, it was a reasonably fun puzzle. I enjoyed SADLOT (reminding me of Ruth's song from Pirates of Penzance, although there it's "... a member of this shy lot."), GHOULS, and especially 48D: What hens do (LAYEGGS). That's fine work right there.