Unlike presidential elections, it is usually quite easy to predict who will win the mid-terms. Two years ago I was one of a tiny minority who did not regard Hillary Clinton as either very likely or virtually certain to be the next president of the United States. I compared the race to that year’s baseball World Series, which had just been ever-so-narrowly won by the underdogs, the Chicago Cubs.
The outsider, Donald Trump, could beat the favourite, I argued, if there was “a differential in turnout between his supporters and hers in the battleground states, comparable to the age- and ethnicity-based differentials in the UK referendum”. And that was exactly what happened.
Today, with just two days left before polling day, it feels different. This time last week, the World Series was all but over because my team, the Boston Red Sox, were crushing the LA Dodgers — our pitchers so ruthless that in the fifth and final game the LA hitters scarcely connected with the ball.
For Red Sox, read Democrats. Even the most committed Republicans I know accept there is only a remote chance they will keep control of the House of Representatives. The consolation is that the Democrats are almost equally unlikely to win the Senate.
Why are mid-term elections so predictable? The answer is that — despite the role of local issues and candidates — they are in large measure referendums on the president’s performance and, as such, perfect opportunities for Americans to display their characteristic fickleness. Having elected someone president,voters are collectively ready to punch him on the nose after just 24 months. The president’s party has lost House seats in every mid-term election since 1946, with just two exceptions: 1998 and 2002.
In the nine elections when the president’s approval rating was below 50%, his party lost an average of 37 seats. Even in the nine mid-terms when the president’s approval rating was above 50%, his party still lost an average of 14 seats. The only two presidents who saw their party gain seats — Bill Clinton in 1998 and George W Bush in 2002 — were exceptionally popular at the time.
So you think President Trump is exceptionally unpopular? Stop watching CNN. Actually, his current 43% approval rating lands him squarely in the middle of the league table. He’s less popular than Johnson in 1966, Carter in 1978, Clinton in 1994, and Obama in 2010 and 2014. But Trump is more popular than Truman in 1946 and 1950, Reagan in 1982 — amazing, isn’t it? — and Bush in 2006.
On Tuesday, Democrats need to win 23 seats to retake the House. Looking solely at Trump’s approval rating, you would expect them to win up to 41, but allowances need to be made for the Republicans’ recent gerrymandering of district boundaries, which should help them hang on to about five seats that would otherwise flip.
Another way to read the tea leaves is to look at the popularity of the two parties themselves, as revealed by polls asking if voters would prefer a generic Republican or a generic Democrat to represent them. Since 1950, a victorious party has never trailed by more than 4.5 percentage points in the week of a mid-term election. Republicans are currently behind by 8.5 points.
Democrats also lead in fundraising, by roughly $1bn (£770m) to $700m. The average Republican challenger to an incumbent in 2010 — the year the Republicans gave Obama his famous “shellacking”— had double the campaign donations of the average Democratic challenger. This year, according to the Campaign Finance Institute, Democratic challengers have seven times more money than Republican ones.
For further evidence that Republicans have a problem, look at this year’s special elections (by-elections in British English), where Democratic candidates have achieved an average 15-point swing. To their dismay, Republicans have found that last year’s tax cuts are a vote-loser. Their hasty shift from economic issues to cultural issues — from “Yet more tax cuts!” to “The caravan is coming!” — has not sufficed to stem the blue tide.
So why is the Senate not going the same way as the House? The answer is that the Democrats are having to defend 26 of their seats — 10 in states won by Trump in 2016 — while the Republicans have only nine seats in play, making it the most skewed contest since 1938. True, incumbent senators from the opposition party tend to win re-election. But in North Dakota and Missouri, the Democratic incumbents Heidi Heitkamp and Claire McCaskill are trailing Republican challengers. Bill Nelson is up against it in Florida. So is Joe Donnelly in Indiana. To win control, the Democrats must hang on to all their existing seats and win two more. Watch Arizona, Nevada and Tennessee; maybe also Texas, where Ted Cruz is battling the charismatic Beto O’Rourke. But don’t be surprised to see Mitch McConnell, the Senate majority leader, still in charge when it’s all over.
If Democrats thought their attempt to derail the confirmation of Brett Kavanaugh as a Supreme Court justice would pay dividends in November, they could not have been more wrong. The hearings at which Kavanaugh was confronted by his accuser, Christine Blasey Ford, backfired as men — and many women — all over the American heartland sided with Kavanaugh.
For a time, I thought the Kavanaugh effect might be sufficient to save the Republicans in the House, too. Anger over the way the Democrats had behaved, scepticism about Ford’s somewhat hazy recollections and sympathy with Kavanaugh’s indignation — this was a powerful cocktail that galvanised my Trump-supporting friends. However, research on social media trends by my former student Gil Highet put paid to this idea. It turns out that, while the Kavanaugh hearings did fire up the Republican base, it fired up their opponents even more in the most hotly contested districts.
So what can we expect if the Democrats do win the House? Of course, there may be no stopping the polarisation. With no meaningful changes to the way Facebook, Google and Twitter operate, American voters are just as exposed as they were two years ago to a barrage of fake news, extreme views and targeted ads. The difference is that the Democrats have learnt their lesson and are now unabashedly waging the info war — big data, bots and all. If elected, “woke” progressives such as Alexandria Ocasio-Cortez fully intend to bring the #Resistance and #MeToo to Washington. Trump’s impeachment will be top of their agenda.
Yet there is another scenario. Unless they do much better than expected, the left will not be able to stop the veteran California Democrat Nancy Pelosi being re-elected as Speaker of the House. She loathes Trump, no doubt. On the other hand, the more Trump talks about imposing tariffs on China or passing an infrastructure bill, the more like an old Democrat he sounds. Moreover, Pelosi has been around long enough to remember what impeachment did for Bill Clinton: his approval rating — already high at the time of the November 1998 mid-terms — rose to 73% the week he was impeached.
Mid-terms may be more predictable than most things in politics. Predicting what comes after Tuesday is a whole lot harder.
Niall Ferguson is the Milbank Family senior fellow at the Hoover Institution, Stanford