Seldom in the recent history of U.S. presidential elections has a candidate dominated the polls as Hillary Clinton does now. Is there room for a surprise? The ex-secretary of state, ex-senator, and ex-first lady will host her first large campaign rally this Saturday, in New York. She is the definite favorite for the Democratic candidacy in the November 2016 presidential elections. No one overshadows her in the caucuses or the primaries, which will choose the Democratic candidate for the White House.

Clinton is almost 50 percentage points ahead of her competitors. According to the latest poll from Real Clear Politics, Clinton has the support of 59 percent of Democrats. Vermont Sen. Bernie Sanders, who is described as a socialist, controls 11.5 percent. Former Maryland Gov. Martin O'Malley holds 2.3 percent. And Lincoln Chafee, former Rhode Island governor and senator, has 0.8 percent. For now, these are the Democratic Party's candidates. It's a small group compared to the Republican Party, which already has a dozen candidates and no clear favorite.

From this perspective, it would appear that Clinton and her rival Democrats could save themselves months of exhausting campaigns, trips in buses and nights in motels, mobilizing thousands of volunteers and millions of dollars that it costs to finance the extravaganza, and gather instead in Philadelphia the last week of July in 2016. That city will host the National Democratic Convention, in which the Democratic candidate that will run against the Republican nominee in the presidential elections will be formally chosen.

But nothing is decided until everything is decided — or, at least, until the Democratic nominee that will defeat the Republican candidate is chosen, and this part seems more difficult. No one knows that better than Hillary Clinton. What could happen to derail her candidacy?

1. Health

Clinton is 67 years old. If she won the nomination and then the presidency, she would be 69 years old when she was sworn in as president. If she had two terms of four years each, the most permitted by the Constitution of the United States, she would leave the White House as a 77-year-old.

Reaching the White House as a 69-year-old is unusual. The only president who began his command at that age was Ronald Reagan in 1981. There has not been an older president. Is this a disadvantage for her campaign?

The Republican Ronald Reagan used age to his benefit during a debate with the Democratic candidate Walter Mondale in the 1984 presidential campaign. The moderator asked Reagan if, given his age — 73 at that time — he believed that he could still function at his full potential during a crisis.

Without a doubt, responded Reagan. And he added what has become a pattern in all presidential debates: "And I want you to know that I won't make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent's youth and inexperience." Mondale was 56 years old.

Clinton's age could be a liability, but it doesn't have to affect her health. The U.S. Social Security’s website allows you to calculate life expectancy by submitting your gender and date of birth.

Clinton, who was born on October 26, 1947, still has 19.4 years to live. According to these calculations, she will die at 87 years old. In other words, 10 years after leaving the White House, if she serves two terms — the calculator states that life expectancy will have increased a little more than half of a year when Clinton turns 70.

Clinton's health came into play in the campaign after she fainted in December 2012, falling and suffering a blow to the head. The doctors later discovered a clot in her head. Clinton did not sustain any neurological damage, but some of her adversaries tried to use the accident to plant doubts about her abilities. Karl Rove, who was an adviser to President George W. Bush, suggested last year, without offering any proof, that Clinton could be hiding details about her health. Since then, Clinton's health has not reappeared in the campaign.

2. Scandals

Another danger for Clinton's campaign are scandals. The word alone doesn't mean much. Clinton has not been implicated in any scandal or in anything illegal. But ever since her husband Bill was president of the United States in the 90s — and even before, when he was governor of Arkansas — her last name has been associated with lack of transparency and manipulation.

Any action by the Clintons is viewed suspiciously by her rivals, by a good part of the country’s journalists, and by many Democrats — the first being Obama, whose doubts about the Clintons’ integrity, expressed rather openly,, eroded Hillary's candidacy against Obama in the 2008 Democratic primaries.

The Republicans can attack Clinton from at least two flanks. The key words are Benghazi and Foundation. In the next six months, we will hear a lot of them.

A. Benghazi

In this Libyan city, on Sept. 11, 2012, an attack on U.S. diplomatic and intelligence facilities took the life of Chris Stevens, the U.S. ambassador to Libya. At first, the Obama administration tied the attack to a protest against an anti-Muslim documentary. It later changed its story and blamed a terrorist group. The Republicans immediately accused Obama and Clinton, who was then his secretary of state, of exposing their diplomats, covering up a scandal, and manipulating the facts. The investigations in Congress have not found any clear evidence.

B. The Clinton Foundation

After finishing his second and last term in the White House in 2001, Bill created his own foundation. The Clinton Foundation — now the Bill, Hillary, and Chelsea Clinton Foundation — is a philanthropic giant. However, the foundation gives the impression that the Clintons sell favors in turn for million dollar donations to the foundation, some from foreign countries. Some people think the Clintons can be bought. A book published in May, “Clinton Cash,” written by conservative Peter Schweizer, sheds suspicion on Hillary Clinton's time in the State Department. The book suggests that favors were given in exchange for donations. No instance of this has been demonstrated, but the shadow extends over the current campaign. Could donors be buying influence in a future President Clinton? There is no proof of that either.

The danger for Clinton would be a sensational revelation about Benghazi, the Clinton Foundation, or another issue, like the private email account that the candidate used when she was secretary of state, or the price of Hillary and Bill's speeches.

The problem for her rivals is the lack of evidence showing illegal or irregular activity. Another difficulty is that after almost 40 years in public life, not a lot remains to be discovered about the Clintons. Few families have been scrutinized as much. This makes it difficult to imagine a new scandal of dimensions great enough to sink a candidacy.

3. Excessive Confidence

The Greeks called it hubris, the mix of arrogance and self-confidence that led humans to believe they were gods. Hillary Clinton's danger is hubris — to believe that she has already won.

In 2007 and 2008, Clinton was called the "inevitable candidate." At that point in the campaign, with less than half a year until the beginning of the primaries, the consensus was that Clinton would be the nominee. Yes, young Sen. Barack Obama had brought multitudes to his rallies, but he was too inexperienced to battle Clinton, the more seasoned candidate and the natural heir to the White House after the Bush years.

Clinton's rivals in the Democratic Party — and many journalists, bored with the idea of an unimpeded coronation — would like to think that in the next months, a new Obama will emerge, someone to compete for the candidate's throne.

"She was also inevitable then," is an argument that is often heard. But the distance between Clinton and her current rivals is much greater than what separated Clinton and Obama.

In June 2007, Clinton had a 15-percentage-point advantage over Obama. Now, she has almost 50 points over her closest pursuer, Sanders.

It is likely that the distance will grow shorter, that Clinton's control will weaken, and that she will suffer some kind of setback in the next few months that will discourage her campaign (see points 1 and 2). But no one imagines a sudden “Sandersmania” or” O'Malleymania” in the style of the “Obamamania” of 2008, the collective fervor that pushed the young senator to victory against the veteran Clinton.

Another option involves the arrival of another more powerful candidate. Two names have been circulating. One is Sen. Elizabeth Warren, unofficial leader of the left of the Democratic Party. But Warren insists that she will not run. She prefers to influence Clinton from the outside than enter a battle that she has very little chance of winning. Another alternative is Vice President Joe Biden, hit by the death of his son Beau on May 30. Biden, a respected figure with experience, was a candidate for the nomination twice, in 1988 and in 2008.

Johnson succeeded Kennedy, Ford followed Nixon, and George H.W. Bush came after Reagan; a vice president who aspires to the presidency is traditional. And a Clinton-Biden battle would have its own particular flavor: two heavyweights of the Democratic Party, omnipresent for decades in the politics of this country, with one advantage for Clinton—she would be the younger candidate. Biden is 72.