(CNN)With Wisconsin and Arizona certifying their states' election results on Monday, there can no longer be any disputing that Joe Biden convincingly beat Donald Trump. There are many reasons for Biden's win. Trump's mishandling of the Covid-19 crisis may have pushed some voters away from him. Similarly, his vulgarity and angry rhetoric may have helped Biden pick up support from educated White voters who had previously voted Republican. And Biden may have been a more attractive candidate to White working-class voters than Hillary Clinton was four years ago.
But a closer look at the 2020 election data, particularly when compared to 2016, reveals that another dynamic was central to Biden's victory: the absence of any strong third party candidate. In 2016, Trump received 46.4% of the vote. Four years later, in a much higher turnout election, Trump did slightly better with 47.1% of the vote. The difference between Clinton's 48.5% and Biden's 51.1% was enough to put Biden over the top.
However, the data suggests that Biden did not so much take support from Trump as get it from somewhere else. That somewhere else was from voters who voted third party in 2016.
Four years ago, 94.9% of voters supported either Trump or Clinton, meaning that around 5% supported a third party candidate, primarily Libertarian Gary Johnson or the Green Party's Jill Stein.
No third party candidate won any Electoral College votes, but they won enough support to be dubbed spoilers who cost Clinton the key battleground states that put Trump in the White House. By contrast, the two major party candidates in 2020 got 98.1% of the vote combined, limiting third party candidates to less than 2% of the vote.
In 2016 the Libertarian ticket included two former governors, New Mexico's Johnson and Massachusetts' William Weld. They were never going to win, but they had the profile of a legitimate national ticket and Johnson's support for marijuana legalization made him even more high profile. Green Party candidate Stein had run previously and was reasonably well known in far-left circles.
This year, the Libertarian candidate was an obscure academic named Jo Jorgensen. Her running mate was Spike Cohen, an online personality and activist. The Jorgensen-Cohen ticket was nowhere near as plausible as Johnson-Weld four years ago.
Presidential elections are not won nationally, but in individual states. Trump won the three key Midwestern states of Pennsylvania, Wisconsin and Michigan in 2016; Biden flipped all of them in 2020. In all of those states, the third party vote in 2016 was greater than the margin of Trump's victory. Four years later, support for third party candidates dropped from 6.4% to around 1.5 in Wisconsin, from 5.7 to 1.5 in Michigan and from 4.3 to 1.2 in Pennsylvania. There is no proof that all of those third party voters from 2016 moved to Biden in 2020, but a far left candidate like Stein likely drew more from Clinton than from Trump in 2016. Johnson's support was more complicated, but there is reason to believe he hurt Clinton more than Trump.
The 2016 election was not the first time that third party candidacies played major roles in presidential elections. Many believe the Green Party's Ralph Nader tipped the crucial Florida vote in favor of George W. Bush in 2000. In 1992, Ross Perot, running as a kind of deficit hawk centrist, won 19% of the vote, leading many to believe -- although the data is less definitive -- that he made it possible for Bill Clinton to win. A generation earlier, George Wallace ran as a White backlash candidate, got 13.6% of the vote and carried five southern states. In the complex political environment of 1968, when today's political coalitions had not yet been formed, Wallace may have helped Richard Nixon win.
Perot and Wallace won many more votes than Johnson or Stein in 2020. Perot pushed concerns about balancing the budget into the center of political discourse. Wallace showed the power of racial resentment politics. By 1972, Richard Nixon was using Wallace's rhetoric to remake the Republican coalition. Wallace's anti-intellectualism and appeal to lower income Whites reemerged in 2016 and 2020 as major themes of Donald Trump's campaigns.
There was a moment in the 2020 race when it looked like a strong, if eccentric, third party candidate might emerge in the person of the entertainer Kanye West. Democrats fretted that a celebrity like West could take enough votes from Biden to keep key states like Michigan in Trump's column. Many suspected that the Trump campaign was involved -- something the campaign denied -- with the efforts to get West to run after he had come out in support of Trump at a meeting in the Oval Office.
There certainly was good reason why Republicans would have wanted the high-profile West to compete with Biden for the Black vote. West's campaign, however, fizzled out. Ballot access can be expensive and difficult for first-time candidates, and issues like missed deadlines meant West was able only to get on the ballot in a few states, where he received a negligible 60,000 votes.
While the failure of any third party to gain traction in 2020 was partly due to the nomination of unimpressive candidates, another explanation may be that voters were less willing to take a chance on no-hopers given the Covid-19 pandemic and the polarizing nature of the Trump presidency. If that polarization remains a fact of American political life -- and we have not seen any evidence to suggest otherwise -- it will remain difficult for smaller third parties to get much support in future elections too.