How flush Americans feel depends on their views of Donald Trump

DONALD TRUMPUS has yet to step back inside the White House but already it is evident that he will dramatically improve the . That, at least, is according to Americans who identify as Republicans. Democrats say the opposite: even before Mr Trump has implemented any of his policies, they are sure he will drive the economy into a ditch.Given that American politics can resemble a blood sport, it is hardly surprising that people’s views differ by party affiliation. But the divergence in economic surveys is remarkable, and has widened since Mr Trump burst onto the electoral scene a decade ago. It now even colours responses to questions that ought to be straightforward, such as whether one’s personal finances are in good shape.The best measure of the split is a monthly survey of consumer sentiment conducted by the University of Michigan. In October, shortly before the election, the index was 91.4 for Democratic respondents—a level consistent with robust economic growth—and 53.6 for Republican respondents—a level seen during recessions. As soon as Mr Trump triumphed, opinions flipped. Republicans are now much more optimistic about the state of the economy (see chart).Other gauges of popular opinion paint a similar picture. A weekly survey by and YouGov, an online pollster, asks Americans to rate their personal finances. On the eve of the election 63% of Republicans said they were worse off than a year ago. Today, that figure has declined to about 48%. Numerator, another online pollster, finds the biggest shift is in expectations. In October 25% of respondents in right-leaning counties said the economy would be better in a year’s time. In November, following the election, 52% thought it would be better.To some degree these results are understandable: Mr Trump’s supporters naturally think he will do a good job. Nevertheless, the partisan gap in economic perceptions is bigger than it used to be. Ryan Cummings and Neale Mahoney of Stanford University have found that Republicans tend to “cheer louder” than Democrats do when someone from their party is in office and also “boo harder” when the opposition is in power. Mr Trump, America’s polariser-in-chief, seems to have accentuated this tendency. According to the latest data from the Michigan survey, the sentiment figure for Democrats is down 27% since the election, whereas the figure for Republicans is up by a whopping 63%.Ultimately, though, perceptions of the economy are affected not just by partisanship but also—as one would hope—by the state of the economy itself. When times are good, views among Democrats, Republicans and independents usually move up in parallel, says Joanne Hsu of the University of Michigan. When times are bad, they typically decline in tandem. Inflation may present a litmus test for Mr Trump. Republicans now believe that prices will rise by just 0.1% over the next 12 months; Democrats, by contrast, predict that they will shoot up by 4.2%. There is, in other words, plenty of scope for Democrats to be pleasantly surprised by Trumponomics—and for Republicans to be rudely awakened.