I keep a database of statistics compiled by Rasmussen Reports. One of the statistics is based on a weekly poll in which likely voters are asked about the direction of the country; specifically, whether it is going in the right direction or is on the wrong track. That’s a vague question, which leaves it up to the respondent to define what’s right and what’s wrong. A respondent might, for example, reply according to how he is feeling at the moment about the performance of the president. Whatever the case, I compute a weekly value for the ratio right direction/wrong track.
A second statistic is a direct measure of the president’s popularity. It is given by the following ratio: fraction of respondents strongly approving the president’s performance/fraction of respondents either approving or disapproving of the president’s performance. (This ratio disregards persons not venturing an opinion pro or con.)
(For more about these two metrics, see this post.)
Take Obama’s eight years as president (please!). Excluding the first several weeks of Obama’ first term, when his stratospheric approval ratings had more to do with hope than performance, here’s the relationship between the two metrics (with right direction/wrong track on the horizontal axis):
There’s a strong but not perfect relationship, which suggests that factors other than the president’s performance affect respondents’ views of the state of the nation. But it is evident that perceptions of the state of the nation do have a strong effect on judgments about the president’s performance (and vice versa).
Given that, the question arises whether Trump gets as much credit (or discredit) as Obama did for the perceived state of the nation. This graph covers Trump’s first term to date, and the same span of Obama’s first term, excluding (in both cases) the early “honeymoon” weeks:
Opinions of Trump have been so poisoned (with help from Trump, himself) that he can’t muster higher approval ratings than Obama did unless voters feel considerably better about the state of the nation under Trump than they did under Obama. A strong-approval ratio of 0.36, for example, was achieved by Obama with a right direction/wrong track ratio of about 0.7, whereas Trump can’t muster a strong-approval ratio of 0.36 unless the right direction/wrong track ratio is about 0.85.
What does that mean for Trump’s re-election? It won’t happen if between now and election day 2020 there is a sharp economic downturn, a severe stock market correction, or a major defense/foreign policy crisis of some kind. An impeachment trial, on the other hand, might be just the thing Trump needs to garner enough independent votes for re-election.