… Lamb’s apparent victory over Republican Rick Saccone the morning after Election Day runs in the hundreds of votes in a contest where more than 220,000 people cast ballots. In the 2016 presidential contest (according to Daily Kos’s invaluable tallies of presidential votes by legislative districts), more than 370,000 votes were cast in the district, with Trump receiving 215,000 of them. Lamb got about 78 percent of the votes that Hillary Clinton received in the district — but Saccone received about 52 percent of the votes Trump received. The result? A tie. A shift of 20 points toward the Democrats.
That shift is not uncommon in special elections since the 2016 presidential race. In 86 special elections we examined since the presidential race, the average shift has been 13.4 points to the Democrats. In 34 races, the Democratic candidate has done at least 20 points better in the district than Clinton did. While the results of those races have been mixed — the Republican candidate has won about half of the special elections — the direction of the shift in the results was in the Democrats’ favor three-quarters of the time. CONT.
Philip Bump, Washington Post