As per the question, it is quite unusual for a party nominee to receive less than 80 percent of the partisan vote either in a presidential race or congressional race as the partisans are the committed or obligated members of a particular political party. These members quite firmly promote and propagate the ideals or policies of their party and very much resistant to accommodate with the opposition or rival parties. Thus, the situation is quite unexpected or rare to receive lesser than 80% of partisan votes(they would support the party they are obligated or committed to).
