Editor's Note: (Julian Zelizer is a professor of history and public affairs at Princeton University and a New America fellow. He is the author of "Jimmy Carter" and "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." The opinions expressed in this commentary are solely those of the author. This is an updated version of an article that ran previously.)
(CNN) Earlier this year, Donald Trump suggested that if the Republican Party doesn't treat him right, he might run as a third-party candidate. Republicans should be worried.
If Trump takes this step, he would add a serious element of uncertainty into an already unwieldy process. Trump can bring his demagoguery and willingness to say anything approach to the general election, when the outcome in a handful of states will determine the next president.
Should he run as an independent, Trump would be following in the footsteps of Ross Perot. In the 1992 presidential election, Perot caused immense trouble for Republican President George H.W. Bush in his campaign against Bill Clinton by entering the race as a self-financed third-party candidate. Like Trump, Perot had the money and media savvy to command national attention even without a formal party apparatus behind him.
Perot, a Texas billionaire businessman, wasn't happy with the direction of national politics. He told the nation he was entering the presidential campaign in April 1992 on CNN's "Larry King Live." Perot paid for his own television ads and did most of his campaigning on television shows, which were more than happy to have the eccentric Texan on the airwaves given that he was willing to say what was on his mind without the kind of filters that most politicians usually depend on.
Perot aggressively attacked President Bush for allowing the national debt to balloon and for failing to fix the economy. He compared the federal deficit to the "crazy aunt we keep down in the basement. All the neighbors know she's there but nobody wants to talk about her." He continually warned that the NAFTA free trade agreement, which President Bush was working on, would quickly drain jobs out of the country (creating a "giant sucking sound") and into Mexico, where labor was cheap and government workplace standards were virtually nonexistent.
Though Perot did not win any Electoral College votes, he did win almost 20 million votes, constituting about 19% of the electorate, the best third-party performance since Theodore Roosevelt ran on the Progressive Party ticket in 1912.
Most experts agreed that his candidacy hurt President Bush, taking away the votes of independent and moderate Republicans attracted by Perot's fiscal conservatism. Perot's onslaught against Bush also damaged the image the entire American electorate had of his job as president, all of which benefited Bill Clinton and the Democrats.
Can Donald Trump do the same in 2016?
As a third-party candidate — with the money that he has to spend and the media attention he can command — Trump can have a bigger impact. As Trump has shown in his attacks, he holds a grudge. If he feels like he was squeezed from the GOP it is likely he would direct his venom toward them in a third-party campaign of retribution.
Trump can cause some pretty big problems for the Republicans. In his most recent incarnation, Trump, as an article in Talking Points Memo points out, is even more conservative than Perot was in 1992. If the real estate mogul continues along the current path, he could rally hard-line elements of the GOP, such as the warriors who are fighting against immigration, siphoning off right wing voters and activists.
For a number of Republicans, such as Jeb Bush, who are already struggling to prove to their conservative base that they are strong and ideologically pure candidates, this will be a problem.
While economic indicators suggest growth will continue, in contrast to the recessionary months of Perot's campaign in 1992, Trump can still appeal to frustrated voters because is there is huge unrest within an electorate struggling with the new normal of ongoing insecurity for the middle class and growing divisions between the rich and poor. The combination of demagogic populist appeals and the lure of his claim that somehow a business person would instinctively do a better job running the government will have appeal to some on the right.
To Republican candidates like Sen. Ted Cruz who are depending on support from the base, a Trump third-party candidacy would force them to compete for the loyalty of voters who otherwise would have been eager to mobilize in the Republican tent.
At the same time, Trump could easily turn his attention back to more business-friendly elements of conservatism, such as fighting against tax increases and regulation, which could attract wealthier suburban voters and business leaders who are uncomfortable with the social and cultural conservatism of a Ted Cruz.
Trump can also hurt the ability of Republicans to build a broader electoral base by continuing to convey the association of "conservatism" with the more radical elements of the political electorate, as he has done recently with his statements about immigration and Muslims and in previous years with his support for the "birther" issue. While he wouldn't be running as a Republican, he would bring down the brand name of the ideology the party sells.
Another problem has to do with the media. Whoever runs for the GOP will need as much media attention as they can get. For all her flaws, Hillary Clinton commands an overwhelming position in the public imagination. She is a known commodity and she is someone who has been a prominent figure in national politics for decades. To the extent that Trump takes away airtime, Republicans, who are less known in the electorate, might find themselves struggling to gain traction on television and online.
Of course, a third-party run by Trump could also cause problems for Hillary Clinton. He wouldn't hold his punches against her and he could land some blows. But the weight of such a candidacy would likely fall on Republicans.
Nor is the comparison to Perot's overall impact a slam dunk by any stretch of the imagination. The electorate is more culturally and socially diverse than it was 25 years ago, and Trump's harsh language on immigration could end up turning off more voters than Perot's economic agenda did in 1992.
Trump's history as a reality television star, which is currently helping him, will also raise the bar for voters to take him seriously as the caucus and primary campaigns really get underway. His record is filled with so many shifts in position that he could bring new meaning to the term "flip-flop."
While the leading Republican candidates probably don't have to worry too much about Trump surging ahead in their own party contests once voting starts in the caucuses and primaries start, they should be really worried about him becoming a third-party candidate. A 2016 version of Ross Perot could cause a lot of trouble for the GOP at the exact moment it is trying to take the White House back after eight years in exile.