Biden vs. Trump Is Bound to Be Close

Three fundamental facts define our current political era: We are deeply divided along partisan lines and are closely divided at the national level, but at the state and congressional levels, jurisdictions increasingly give supermajorities to one party. This environment produces presidential elections with narrow national popular-vote margins decided by a small share of the electorate in a dwindling number of swing states.

Based on the evidence thus far, 2024 isn’t likely to break this pattern, which has increasingly defined U.S. politics since the late 1980s. RealClearPolitics’ widely cited average of polls shows President Biden, the likely Democratic nominee, leading Donald Trump, the likely Republican nominee, by less than 1 percentage point. A recent Wall Street Journal poll has them in a dead heat, 46% to 46%. In such a close contest, defections to independent and third-party candidacies can be decisive, as they were in 2016.

If Messrs. Biden and Trump end up as the standard bearers of their parties, the 2024 presidential election will be unlike any that we have seen in our lifetime. Not since 1892 have the president and the incumbent he defeated had a rematch.

In nearly all elections featuring a president seeking re-election, the election is mostly a referendum on the incumbent’s performance. If voters think he has done a good enough job to deserve another term, he will almost certainly win, no matter the merits of his challenger. The 1956 election, in which President Dwight D. Eisenhower handily defeated former Illinois Gov. Adlai Stevenson, is a good example. If the people don’t think the incumbent has done a good enough job, they ask themselves whether it would be safe to entrust the powers of the presidency to his challenger. Ronald Reagan didn’t secure victory until he reassured voters that he wasn’t a reckless extremist during his debate with Jimmy Carter in late October 1980.

The 2024 election, by contrast, won’t be a referendum on the incumbent but a choice between two men who have occupied the Oval Office and whose agendas and governing styles are known. In these circumstances, Mr. Biden has less of the advantage incumbents usually enjoy, but Mr. Trump has a presidential record to defend, not only an incumbent’s record to attack.

On the personal level, Mr. Biden’s age is seen as a problem by a swath of the electorate, but so is Mr. Trump’s conduct after the 2020 election. Mr. Biden is seen as more honest and likable, Mr. Trump as a stronger leader with a better record of accomplishment in office.

Each candidate is a hostage to fortune. Mr. Biden’s chances for re-election will be affected by developments in the economy and on the battlefields of Ukraine, while Mr. Trump’s effort to enter the Oval Office will be shaped by the multiple trials in which he is embroiled. No one knows whether swing voters would support a candidate who has been convicted of a felony.

Each candidate will be challenged to address an issue that he and his party have mishandled, to the consternation of the electorate. For Mr. Trump, the problem is abortion. Although the Supreme Court’s decision overturning Roe v. Wade was hailed by pro-life groups, it has thrown the Republican Party into disarray. Some favor leaving the issue to the states; others urge national restrictions on abortion but don’t agree on what the limits should be. Intensified controversy over abortion helped Democrats limit their losses in the 2022 midterm elections, and the outcome of state referendums suggest that the issue hasn’t lost its power to mobilize outraged supporters.

While Mr. Trump has urged his party to be flexible, he can’t evade responsibility for the current controversy. Fulfilling a promise he made during the 2016 campaign, he appointed three Supreme Court justices whose votes were decisive in overturning Roe, something the Biden campaign won’t let voters forget.

But Mr. Biden faces his own intractable issue—immigration. During his first two years in office, internal divisions deadlocked his administration. The policies he finally put in place in early summer produced a temporary reduction in the flow of illegal immigrants. But last month record numbers of migrant families streamed across the southern border, and as many moved on to cities far beyond the Southwest, division broke out within the president’s party. New York Mayor Eric Adams has clashed with Gov. Kathy Hochul and has repeatedly criticized Mr. Biden’s handling of the issue. Several congressional Democrats have joined Mr. Adams.

This growing controversy reflects a Democratic Party deeply divided between progressives who oppose most restrictions on asylum-seeking immigrants and centrists who oppose open borders. Voters give Mr. Biden even lower marks for his handling of immigration than for most other issues. And like abortion, it will not lose political potency between now and November 2024.