The only thing holding up the President’s approval numbers is the fact that the economy is on a roll. Trump became President 7 years after the end of the Great Recession that began under President Bush. The climb out of the recession was slow and as the economy was peaking in its business cycle, Trump further stimulated it by cutting taxes. I contend this will come back to haunt us we are living on borrowed money. But putting that aside, it had the effect of further lowering the unemployment rate. Despite an expanding economy, Trump’s approval numbers hover around 40 percent and more people disapprove of his performance than approve. (How can that be an “A+”?)
To determine how much the good economy has been propping up Trumps approval numbers, I analyzed his monthly approval ratings as compared Obama’s ratings in his last two years of his presidency using Gallup data. I ran a simple regression model. The monthly approval rating is a function of the monthly unemployment rate (from BLS) and a variable denoting the different presidents. Controlling for the unemployment rate, Obama’s approval rating was 21.4 percentage points higher than Trump’s rating. Similarly, when I used the difference in the disapproval and approval ratings, I found that Trump’s disapproval gaps exceeded Obama’s by 13.4 percentage points.
The approval rating model also reveals that a the one point rise in the unemployment rate causing the presidents’ approval rating to fall by 3.7 percent. That means if Trump experiences the 5.7 percent unemployment that Obama had to deal with at the start of 2015, his approval rate would fall 7.4 percentage points. This would put his approval rating down near 30 percent.
Economic expansion typically lasts just over 3 years (about 39 months (Investopedia)). In modern times the economic expansions have lasted longer, averaging close to 5 years. The current expansion began in June 2009 and has been going for 9.5 years. If it lasts until the summer, it will be 10 years and the longest period of expansion in US history (CNN). It is hard to imagine it will last until 2020.