President  Trump and Britain’s prime minister, Theresa May, right, leave after a “retreat meeting” on the first day of the G-20 summit in Hamburg on July 7. (Tobias Schwarz/AFP/Getty Images)

Despite winning the presidency, Donald Trump is a historically unpopular political figure. He had the lowest favorability ratings of any modern presidential nominee during the 2016 campaign, and he is  less popular than any  president in the history of modern polling has been at this point in his term.

As unpopular as President Trump is in the United States, he is even more disliked in Western Europe. The graph below from Pew’s Global Attitude Project shows that confidence in Trump to do the right thing in world affairs ranges from 7 percent in Spain to  22 percent in the United Kingdom. That represents a huge decrease from Pew polls conducted while Barack Obama was in office.

A sizable majority in the U.K. were not happy that  Trump was elected president, either. Right after he won the presidency, 65 percent of respondents in a November-December 2016 British Election Study survey said they were disappointed by Trump’s victory over Hillary Clinton, while only 15 percent were happy about it.

It’s no surprise, then, that the Labour Party’s leader, Jeremy Corbyn, regularly contrasted his opposition to Trump with the Conservative Prime Minister Theresa May’s “subservient” relationship with Trump. Pro-Labour videos even featured May and Trump holding hands during her January 2017 visit to the White House.

Corbyn’s attacks on May’s relationship with the president intensified in the final week of the campaign after Trump withdrew the U.S. from the Paris Climate Accord and attacked the Labour mayor of London, Sadiq Khan, for his response to the June 3 London Bridge terrorist attack.  Both of Trump’s actions were broadly condemned across the U.K. in the days leading up to the election.

So, could Trump have really affected the U.K. election? Several commentators have suggested that May’s embrace of Trump contributed to her party’s unexpectedly poor performance on election day. Although Conservatives expanded their vote share from 37 percent in 2015 to 42 percent in 2017, Labour’s vote share rose at an even greater rate (from 30 percent to 40 percent).  The upshot was that Conservatives lost 13 seats in the House of Commons and their parliamentary majority.

Now we have even more direct evidence of a “Trump effect” in election. The British Election Study (BES) has collected some remarkable data: Their ongoing 2014-2018 Internet Panel interviewed the exact same 7,616 individuals eight different times between May 2015 and June 2017 — including after the U.K. General Election in May 2015, after the U.S. election in November 2016, and after the U.K. General Election in June 2017. Thus, we can determine whether reactions to Trump’s election affected the Conservative Party’s changing electoral fortunes from 2015 to 2017.

The results indicate that there was indeed a Trump effect on the U.K. Election. Here is the relationship between voters’ reactions to Trump’s victory and their support for the Conservative and Labour parties in both 2015 and 2017.


(Graph by Michael Tesler. Source 2014-2018 British Election Study Internet Panel. Note: Numbers represent the weighted sample size for each response choice, with 2015 sample sizes on the bottom and 2017 on top.)

The left-hand panel shows that Conservatives expanded their vote share from 2015 to 2017 among the minority of voters who were happy Trump won. That growth came largely at the expense of the U.K. Independence Party, thanks to its post-Brexit collapse. But perhaps more importantly, the graph shows that May’s party lost votes among the majority of voters who were disappointed by Trump’s victory.

The right-hand panel shows the exact opposite pattern for the Labour Party. Labour’s vote share increased by about 10 percentage points among voters who were disappointed that Trump won, compared to just a five-point increase among Trump supporters.

With nearly two-thirds of voters in the U.K. disappointed by Trump’s victory, Labour’s superior performance among this majority helped the party in 2017.  Meanwhile, Conservatives’ inability to expand on their 2015 margins among voters opposed to Trump appeared to hurt them.

Of course, this doesn’t mean Trump was the only, or even the most important, reason for the Conservatives’ poor performance. But even after controlling for Brexit support, attitudes about immigration, left-right ideological placement, age and gender, reactions to Trump’s election were still associated with vote change from 2015 to 2017.  With all of those factors accounted for, voters who were very happy about Trump’s election were about 15 percentage points more likely to switch to the Conservatives than voters who were very disappointed.

There has been a similar Trump effect on public opinion in the United States as well. Americans with unfavorable opinions of Trump are now more opposed to his signature border wall and more supportive of Barack Obama and Muslims than they were before the 2016 presidential campaign. In fact, some of Trump’s biggest campaign foils — immigrants, Muslims and Obamacare — are all approaching record popularity.

At home, this Trump effect makes it more difficult for the president to pass his legislative agenda. Not only does the spillover of unpopularity from Trump into his policy proposals decrease support for them (see: Trumpcare), but Republican members of Congress must also worry about hitching their wagon to the party’s historically unpopular president.

The Trump effect in the U.K. election shows that foreign leaders might also need to worry. As public opinion turns sharply against the president in most countries, more leaders may find it advantageous to distance themselves from Trump.

Michael Tesler is associate professor of political science at UC Irvine and author of “Post-Racial or Most-Racial? Race and Politics in the Obama Era.”