Rarely is a presidential candidate on a glide path to the White House, with unexpected developments known for derailing momentum.

While President Biden and former President Trump easily clinched their parties’ nominations, and the race has largely proceeded as anticipated, a game-changing situation or two could upend the race in the six months before November’s election.

Several issues are already simmering, from global crises the White House is managing to Trump’s legal troubles.

Here are five possible twists that could shake up the presidential race in the coming months.

Health concerns force Biden, Trump from the race

Biden, at 81 years old, and Trump, who will be 78 on Election Day, are the two oldest presumptive major party nominees in U.S. history. 

While murmurs among commentators about the parties choosing someone else have largely quieted down, some health event sidelining one or both candidates before November does not seem inconceivable. 

Both candidates have emphasized their ability to serve as president amid questions about their physical and mental health. 

In February, Biden’s physician wrote, following a physical exam of the president, that he is “fit for duty” and does not have any new health conditions. 

Trump’s physician released a letter in November saying that he is in “excellent health,” his labs were within “normal health limits” and his cognitive exams were “exceptional.” But the letter was considerably vague and did not provide specific details on what the labs showed. 

Neither has a publicly diagnosed, significant health condition, but a major medical event remains a possibility for both men, as even younger presidents have experienced in the past. 

A wider international conflict breaks out

International turmoil is already a backdrop of the presidential race with two major conflicts ongoing. And despite U.S. troops not directly engaging in either conflict, the political impact is being seen. 

The Biden administration had been pushing congressional Republicans to approve additional financial support for Ukraine in its war with Russia for months before the aid package passed last month. 

At the same time, Biden has been navigating a tricky situation with the war in the Middle East, which has exacerbated tensions within his coalition from 2020. Protests have popped up on college campuses in recent weeks in opposition to continued financial aid for Israel. 

Critics have also organized an effort to vote “uncommitted” as a protest against Biden in the Democratic primaries. 

So far, both these conflicts have not pulled the U.S. in directly. But if they were to spill over if Russia were to attack a NATO country, for example, or Iran were to get more involved in the Israel-Hamas war direct military involvement may be deemed necessary. 

That kind of development could boost or set back Biden’s campaign depending on the public’s view of the conflict. 

RFK Jr. or other third-party candidates gain more traction

Despite the third-party candidates in the race mostly polling in the single digits, both major parties have recently gone on offense against independent candidate Robert F. Kennedy Jr., who has at times polled just above 10 percent. 

The Democratic National Committee has formed a team to address third-party and independent candidates running this year. Trump has also recently turned his attention to Kennedy, calling him a “Democratic plant” and “not a serious candidate.” 

Even with Kennedy sometimes cracking double digits, he would still need to improve to potentially make the debate stage in the fall. If he does, the first three-person general election debate in three decades could add another element of unpredictability. 

In addition to Kennedy, Cornel West is running as an independent, and Jill Stein appears likely to be the Green Party nominee again. Still, both are receiving no more than 1 or 2 percent support in the polls currently. 

A surge for one or more of these candidates could change the outlook for the race. While they’re all long shots for the presidency, a rise from any could yield uncertain results. 

Economy experiences a downturn or recession

The economy regularly is a key campaign issue in presidential elections, and polls have shown the topic to be a top concern for voters this year. 

Although unemployment has consistently remained at a historically low rate under 4 percent, polls show many Americans are pessimistic, especially in light of lingering inflation that has dropped significantly in the past year but remains above the Federal Reserve’s target of 2 percent. 

Biden has sought to balance emphasizing his administration’s success in maintaining low unemployment with recognizing the continued higher prices raising the cost of living. While the economy remains stable, that could be a viable strategy. 

But if an economic downturn or a recession were to happen, Biden would be in a considerably tougher spot to try to convince Americans of his economic message. On the other hand, a drop in inflation allowing the Fed to lower interest rates for the first time in months could spark the optimism that the president needs. 

Trump is convicted or acquitted in New York case

The twist that is most expected to come as soon as a few weeks from now is the return of a verdict in the first criminal trial of a former president. 

Trump’s trial over alleged hush-money payments made to adult film actress Stormy Daniels has been ongoing for a few weeks and could wrap up before the summer starts. The trial may be the only one of the four cases Trump is facing that takes place before Election Day. 

If Trump is found not guilty, he will likely declare victory and that it proves the charges were politically motivated, as he has claimed. 

If Trump is convicted, it would be unprecedented, but the impacts are unclear. Polling has been mixed on whether a conviction in this case would notably hurt Trump. 

One poll found 57 percent of those surveyed consider the hush-money charges to be serious, and the same amount say Trump shouldn’t be president if convicted of a serious crime. Another poll found that those who said a conviction would make them reconsider support for Trump overwhelmingly would not vote for Biden. 

But even a small change one way or another could make the difference.