Presumptive Democratic presidential nominee Hillary Clinton, left, and presumptive Republican presidential nominee Donald Trump. (Agence France-Presse via Getty Images)

Doug Sosnik, a Democratic political strategist, was a senior adviser to President Bill Clinton from 1994 to 2000.

If history is any guide, the outcome of this year’s presidential election has already been decided.

With the exception of 2000, the result of every presidential election since, and including, 1980 has been determined before the general election even officially began. In fact, most of these elections were effectively decided by this point in the cycle.

A Washington Post-ABC News poll shows Democratic presidential candidate Hillary Clinton taking a double-digit lead over Republican presidential candidate Donald Trump and a higher percentage of Americans saying she's qualified to serve as president. (Sarah Parnass/The Washington Post)

There is no reason to think that this year, as crazy as it has been, will be different. Spoiler alert: Hillary Clinton wins.

The single best predictor of the electoral outcome is the job approval of the incumbent president — even one who’s not on the ballot. In four of the five elections since 1980 when the incumbent president’s job approval was at or above 50 percent, that party held the White House. The outlier was 2000, when President Bill Clinton enjoyed a 57 percent job approval rating in October yet Al Gore “lost” to George W. Bush.

In the three elections when the incumbent’s job approval fell below 40 percent in the final year of his term, the party suffered overwhelming defeats.

Some might argue that Jimmy Carter’s experience in 1980 disproves my point about races being decided by this point, but it doesn’t. True, Carter was leading in national polls in a three-way race (remember John Anderson?) until mid-October. But by June 1980, Carter’s job approval had dropped to 31 percent — and it never significantly improved during the remainder of the campaign.

The nature of a three-way race masked the core of public dissatisfaction with Carter and prolonged until the end of the election the consolidation of the nearly 70 percent anti-Carter vote, which ultimately resulted in Ronald Reagan’s landslide win. By the beginning of the summer of 1980, with 2 out of 3 Americans disapproving of Carter’s performance in office, there was little doubt that the country would not give him four more years.

Three big election moments remain: the selection of the vice presidential nominees, the party conventions and the fall debates. Breathless coverage notwithstanding, none of these has had a measurable impact in changing the outcome of a presidential election in at least 40 years.

The last time a vice presidential selection may have altered the outcome was in 1960, when John F. Kennedy’s choice of Lyndon B. Johnson assured Democrats of carrying Texas.

The last time a party’s convention may have changed the outcome was in 1968, when the Democrats suffered four days of rioting in the streets of Chicago.

And the last time a debate may have affected the outcome was in 1976, when Gerald Ford mistakenly asserted that “there is no Soviet domination of Eastern Europe,” effectively ending his surge against Carter.

All indications are that the 2016 campaign is likely to continue this pattern.

President Obama’s job approval rating now sits above 50 percent. Significant structural advantages have also favored Democrats since 1992. The party’s candidate has carried 18 states plus the District of Columbia — totaling 242 electoral votes — in every election since 1992. Now New Mexico and its five electoral votes, which Bush won in 2004, are considered safely Democratic. If those states remain solid for Clinton, that leaves her only 23 votes short of the 270 necessary for victory.

Demographic trends since 1992 only reinforce this advantage for Democrats. In addition, Clinton enjoys a significant financial and organizational advantage over presumptive Republican nominee Donald Trump. In the past month, the Clinton campaign has run $23 million worth of ads in eight swing states without any time purchased by the Trump campaign to counter her attacks. Clinton has also maintained a stable campaign team at the top while building a national campaign staff of about 700 people. The Trump campaign, on the other hand, has had constant leadership turmoil with a staff of fewer than 100 people.

Lastly, and perhaps most important, never before has a party nominated a candidate as unpopular as Trump is. True, Clinton’s negatives are high — but Trump’s are even higher, reaching 70 percent with more than half having a very negative view.

And Trump’s party isn’t helping him. According to a recent Bloomberg poll, just one-third of Americans have a favorable view of the Republican Party. Some 28 percent of self-identified Republicans have an unfavorable view of their own party.

Americans view their vote for president differently than for any other office. Ultimately, this is a decision as much emotional and instinctual as it is intellectual. And once voters have made that choice, it is very difficult to dislodge.

Voters have gotten to know Trump over the past year. They have pretty much made up their minds about how they feel. It is very unlikely anything that happens in the remaining 131 days of this campaign is going to change that.