Across the street from my home in Cambridge is a branch of the public library bearing a large mural of Tip O’Neill. On the lower left-hand side of the mural is a sign emblazoned with the late speaker’s catchphrase: “all politics is local.”

That slogan was certainly true in Tip’s day. In 1972, a young man named Joe Biden defeated longtime incumbent Republican senator J. Caleb Boggs. On the same day, Richard Nixon carried Delaware by 20 points. Ticket splitting — when a voter picks, say, a Democrat for president but votes Republican for Congress — used to be a major factor in American politics. After Lyndon B. Johnson signed the Voting Rights Act of 1965 into law — and in so doing signed away the formerly navy-blue Solid South — Republican presidents held the White House for almost 24 uninterrupted years, save only Jimmy Carter’s singular term. These were not narrow victories either: Nixon won 61-38 1972, Reagan won 59-41 in 1984 and HW Bush’s relatively narrow 53-46 1988 victory would be considered a landslide today. 

And yet throughout this period, Democrats held the House of Representatives with comfortable majorities. On the same day that Ronald Reagan cruised to reelection, House Democrats won 253 seats. In the aftermath of the 2008 financial crisis, they won 257. Tip O’Neill remained House Speaker because, in 1980, lots of people voted Reagan for president and picked a Democrat for Congress. 

Ticket splitting has been in decline for decades, with political scientists pointing towards increased ideological polarization and better-informed voters as the cause. Back in the 1970s there were liberal Republicans like Vice President Nelson Rockefeller who were arguably to the left of Dixiecrats like Mississippi senator, and notorious segregationist, James Eastland. According to DW-NOMINATE, a metric which calculates ideological scores for members of Congress based on voting records, West Virginia Joe Manchin — the most conservative Democrat in the Senate today — is still to the left of the most liberal Republican, Maine’s Susan Collins. 

In gubernatorial elections, which are more divorced from national politics than Senate races, you tend to see more ticket-splitting. Phil Scott, a liberal Republican, and John Bel Edwards, a conservative Democrat, are the governors of Vermont and Louisiana, respectively, both states typically hostile to their parties. But both men have won multiple gubernatorial races because they have put substantial distance between themselves and the national party on issues such as abortion: Scott is vocally pro-choice, Edwards is vocally not. 

Back in the day, popular governors would often go on to win Senate races in states that favored the other party on the strength of their personal brands — see Manchin or Indiana’s Evan Bayh — but that doesn’t happen anymore. When the two parties were less ideologically sorted, partisanship might’ve been a less reliable predictor of how a senator would vote than their individual positions. But these days, you can get a pretty good idea of a candidate’s position on abortion or taxes or immigration by looking at whether they have a “D” or an “R” next to their name — and voters know this. More importantly, they know that partisan control of a branch of Congress is the decisive factor in what legislation gets passed and what doesn’t. 

Tim Ryan and Joe Donnelly both ran for Senate in right-leaning states — Ohio and Indiana — and publicly aligned with Trump on key issues — namely, trade and immigration. Both lost. Roy Moore, an alleged child molester, came within 22,000 votes, out of 1.3 million cast, of winning a Senate seat in Alabama. How was the race so close? Because Roy Moore is a Republican and Alabama is a very Republican state, so many voters, accurately, perceived a vote for the Democratic candidate as a vote for Chuck Schumer as majority leader. 

But the decline in the number of ticket splitters doesn’t mean that politicians should abandon persuasion and seek to win purely by energizing and turning out the base. For one, convincing someone to vote for you instead of your opponent is worth two votes, whereas getting a nonvoter to vote for you is only worth one. Research has also found that getting nonvoters to turn out for you is roughly twice as hard as flipping a swing voter, and that attempts to turn out your base by running a more ideological candidate often backfire and lead to the other side turning out in even higher numbers.

With fewer and fewer voters being up for grabs and campaigns often being won by razor-thin margins, the remaining persuadable voters are even more important. Last year Brian Kemp was re-elected Georgia governor, beating Stacey Abrams 53-46. Republicans won every other statewide office by similar margins — except for the Senate race, where Raphael Warnock won in the runoff. How did he pull it off? By running ads where Kemp voters vouched for his personal integrity.

MILAN SINGH is a first-year in Pierson College. His fortnightly column, “All politics is national” discusses national politics: how it affects the reader’s life, and why they should care about it. He can be reached at milan.singh@yale.edu.