By Julian Zelizer

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 “The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society” and co-editor of a new book, “Medicare and Medicaid at 50: America’s Entitlement Programs in the Age of Affordable Care.” The opinions expressed in this commentary are solely those of the author.

At least until this weekend, Donald Trump has kept defying all expectations. The political experts (myself included) were predicting that he would fizzle as a candidate soon and were viewing Trump 2016 a political fad, a fringe candidate who has captured the attention of reporters.

Yet for almost two months, he stayed in the game. And Trump has been impacting the competition for several months. His poll numbers kept rising. He has been far ahead of many candidates who are seen as much more effective politicians.

During the first Republican debate, Trump continued to capture the imagination of reporters and voters by talking tough against his opponents and occupying center stage. He was the main attraction in a show that broke records for viewership. “Donald Trump steals the show, mixing politics and pizazz,” stated the headline of The New York Times.

The odds are still strong that the euphoria will soon fade away — as the scrutiny about his past sets in and he continues to make insulting statements — and he won’t be the candidate running against the Democratic nominee in 2016. This weekend big tensions emerged within his campaign as consultant Roger Stone left and Trump’s tirades against Fox host Megyn Kelly stimulated a backlash among conservatives.

But Trump’s campaign has shown more serious political legs than most people expected. At a minimum, his dominance in the political news over the summer has greatly damaged some of the GOP candidates who are trying to take down the well-financed campaign of Jeb Bush.

Right at the time they have been trying to generate attention for their campaigns, Trump has stolen the spotlight. Some of them, such as former Texas Gov. Rick Perry, didn’t even get into the prime-time debate.

Why his message resonates

What happened? Why has this lasted so long? Obviously part of the answer just has to do with Donald Trump. The experts underestimated his skills at the political game. He has proven to be savvier and more astute at electoral politics than most people thought. At some level, he has a message that resonates.
But a lot of his recent success has not been about Trump but about bigger trends shaping the election and the political process, all of which have given him room to mount a substantial effort.

There is an anti-establishment feeling that is clearly shaping electoral politics. There is great frustration with the leadership of both political parties and the entire political system. The base of both parties don’t have confidence that their candidates will speak to their concerns. There are widespread fears that the political system has been corrupted by money and lobbyists.

In a very different way — grounded in a strong grassroots mobilization and guided by a clear set of principled, political ideas — Vermont Sen. Bernie Sanders has tapped into these fears with his challenge to Hillary Clinton. Donald Trump, without a movement behind him and without any clear philosophy other than the virtue of Trump, has appealed to the same sentiment among Republicans who don’t have confidence in the “inevitable” candidates.

Although Trump is tapping into this anti-establishment anger, he is very much drawing on his connections to the establishment, namely money. Trump is no stranger to politics. He has been a longtime political donor, including to many Democrats. Trump himself commands a massive war chest which is allowing him to fund his own campaign. During the debate, he noted that he had donated to most of the other candidates on the stage as well as to Hillary Clinton and said that she attended his wedding.

Without limits on what individuals can spend, he can keep spending as much as he wants. The changes in campaign finance that we have seen over the past decade with the total erosion of the Watergate reforms from the 1970s are offering candidates with their own money or access to Super PACs the opportunity to make a run for the presidency regardless of how deep their appeal is in the electorate.

Since the voting does not begin for over five months, and Trump has deep pockets, there is not much incentive for him to stop competing in this very long pre-caucus/primary phase of the campaign.

Celebrity advantage

Trump naturally thrives in a celebrity culture where Americans are obsessed with the rich and famous. We love to watch reality shows, read gossip columns and talk about people who everyone else knows. Of course, celebrity has always had a role in American politics. Voters love the spectacle as much as the substance. But now the dynamic seems to be getting stronger than ever before.

Trump stepped into this campaign with a huge preexisting fan base from his exploits as a real estate mogul and his starring role in “The Apprentice.” In the game show setting of the first Republican debate, he couldn’t have been more comfortable. This fame offered him the kind of advantage which did not exist with candidates like Herman Cain.

He is capitalizing on his fame in the world of politics in the same way Arnold Schwarzenegger used his celebrity to rise to the governorship of California. Now there seems to be a new Terminator in town.

It is true that media attention is the main engine behind his rise in the polls. But that media surge is proving capable of going on for a long time since there are so many news outlets in the age of the Internet, apps, and cable television covering the primaries and doing so on a 24-hour basis. He provides great copy and reporters are happy to keep this story going.

Trump is also doing well because there is clearly a problem with the party’s presumed frontrunner: Jeb Bush. For all of his political strengths –the fundrising prowess he has displayed and the endorsements from party leaders, all which will be crucial to victory — he has run a lackluster campaign and made a surprising number of gaffes, such as his statement, which he has clarified, about the government giving too much money to women’s issues. Trump does well partly because Bush struggles. With stronger opposition, his maverick candidacy would have had much less appeal.

Shock and awe politics

Finally, Trump knows that this is a period where voters like shock and awe politics. Although people always complain about this, it is exactly what we want.

Voters like a good show, they like to see a candidate who is willing to stun the pundit class by saying things that don’t seem permissible. The Trumpinator, as Jon Stewart called him a few months ago, is doing this with a vengeance. Some of the harsher comments that he has made, such as his comments about immigrants, find an enthusiastic audience in certain Republican circles.

So in many ways it makes sense why Trump’s 15 minutes on the political stage have lasted so much longer than we thought. Does this all add up to winning the nomination? It is still extremely doubtful. As Lynn Vavreck has written in some very smart pieces in The New York Times, the basic fundamentals — party endorsements and fundraising — are still the best determinants of victory.

Last week John Kasich and Marco Rubio turned in very strong performances at the debate that demonstrated they can be serious contenders for the nomination. Over the weekend the turbulence in the Trump campaign suggested that the balloon might finally pop.

But it’s hard to deny that Trump has shown that there is more room than we thought to challenge the fundamentals. As a result, he has caused some pretty big headaches for the rest of the Republican field.

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