With one month to election day, the contest between Donald Trump and Kamala Harris is the electoral equivalent of a bare-knuckle brawl.

The race for the White House still appears deadlocked, both nationally and in battleground states, so victory will be decided by the slimmest of margins - every new voter engaged, every undecided voter swayed, could help land a knock-out punch.

“In any super close race, where the electorate is divided down the middle, a difference of a percentage point or two could be decisive,” says David Greenberg, a presidential historian at Rutgers University.

While party strategists are focused on how to earn that decisive edge, it could just as easily be an event out of their control, an unexpected twist, that upends the campaign in the final weeks.

It’s already been a year of political shockwaves - from one candidate surviving two assassination attempts and being convicted of a crime, to another, President Joe Biden, dropping out of the race in favour of his much younger vice-president.

However, when the surprises drop in October - think Trump’s Access Hollywood tape or Hillary Clinton’s emails in 2016 - there is scarcely time left to recover or regain momentum after a misstep or bad news cycle.

This week alone, there were several new rumbles that could turn into political storms by 5 November.

The first potential political storm was a literal one. Hurricane Helene tore through two key electoral battlegrounds last week, Georgia and North Carolina. Because of the intense focus on both states during this presidential race, a humanitarian disaster, with a death toll already over 200, has also become a political issue.

Harris pledged long-term aid to the region at a stop in Georgia earlier this week, and visited those affected by the storm in North Carolina on Saturday.

"We're here for the long haul," she said in Georgia.

Meanwhile, both states are essentially must-wins for Trump, and polls show a dead heat. While visiting Georgia, the former president claimed that Americans were losing out on emergency relief money because it had been spent on migrants. In fact, the two distinct programmes have separate budgets, and the Biden administration accused Republicans of spreading "bold-faced lies" about funding for the disaster response.

When disaster strikes, it's not easy for the government to keep everyone happy. If Trump’s attacks land, any voter dissatisfaction with recovery efforts could potentially impact the result in two of the most closely-watched states in the country.

Thousands of miles from the disaster-ravaged American southeast, a manmade crisis continues to inject itself into American politics. The Gaza war is in danger of expanding into a regional conflagration, as Israeli forces fought Hezbollah forces in southern Lebanon and Iran launched hundreds of missiles at Israel earlier this week.

While Harris has presented herself as a candidate of change, she put no distance between herself and the current administration when it comes to US-Israeli policies. That comes with risks.

Hopes for any kind of pre-election ceasefire in Gaza appear firmly dashed, and the White House at this point is trying to ensure that the inevitable Israeli response to Tuesday’s Iranian strike doesn’t lead to all-out war.

On Thursday night, Biden was not exactly reassuring.

“I don’t believe there’s going to be an all-out war,” he said. “I think we can avoid it. But there’s a lot to do yet.”

The war is also having consequences at home for Democrats, even if American voters usually don’t think directly about foreign policy when they cast their ballots.

Harris’s commitment to continue supplying arms to Israel is a problem for two key segments of the Democratic base: Arab-Americans in the must-win state of Michigan, and young voters on campuses, where anti-war protests could start up again.

The conflict in the Middle East has also fuelled pocketbook concerns. Biden’s mention of the possibility that Israel would target Iranian refineries caused the price of oil to jump more than 5% on Thursday.

If there’s one thing that American consumers are particularly sensitive to, it's higher prices at the petrol pump.

Across the board, public opinion surveys continue to show that the economy is the top issue for American voters. And Harris and the Democrats received some good news on that front on Friday, with the latest employment figures showing robust job growth over the past few months and an unemployment level that dropped to 4.1%.

According to Mr Greenberg, however, voter concerns on the economy are about more than the latest job figures.

“When people complain about the economy, what they’re really complaining about is the longer-term failure in certain parts of the country - rural America’s de-industrialised communities,” he says. “Those are parts of the country that are hurting even in a good economy.”

For most of the election season, Trump has fared better than Harris when voters are asked who they think would do a better job with the economy, including in a recent CNN poll. But there are signs his lead may not be set in stone, such as a Cook Political Report survey of swing states that showed the two candidates tied on who would be best at dealing with inflation.

One looming economic pitfall for Democrats also evaporated this week - the dockworkers strike, which had briefly shut down critical ports on the East Coast and the Gulf of Mexico for the first time in 50 years. Both parties agreed to return to the bargaining table in January, re-opening the ports. If a work stoppage had continued, it could have disrupted supply chains and driven up consumer prices in the weeks before the election.

Meanwhile, undocumented crossings at the US-Mexico border have returned to pre-Covid pandemic levels, after hitting a record high of 249,741 last December.

While the impact of that border surge is still being felt in many American cities, the urgency of the crisis may be diminishing.

While much of this week’s news could spell trouble for Harris and the Democrats, it wasn’t all smooth sailing for Trump.

His conduct during the 6 January attack on the US Capitol once again came into focus on Wednesday, when a federal judge released a document from special counsel Jack Smith outlining his case and evidence against Donald Trump for trying to overturn the 2020 election result.

The document, which argued that the former president should not be given presidential immunity from prosecution, contained new details about Trump’s words and actions leading up to the Capitol riot by his supporters.

A recent CNN poll shows that voters favour Harris over Trump on issues of “protecting democracy” by 47% to 40% - so anything that renews attention on the chaotic final weeks of Trump’s presidency could be to the Democrat’s advantage.

The term “October surprise” has been a fixture in American political lexicon for nearly 50 years. Campaigns dread the unexpected headline or crisis that pushes their candidates off message and changes the trajectory of a race.

Even the smallest ripple in public opinion might deliver the White House in a year when the electoral margins in the swing states could be measured in only tens of thousands of votes.

November’s balloting, says Mr Greenberg, is shaping up to be a nail-biter.

“I don’t have any fingernails left,” he says. “I could totally imagine this election going either way with extremely significant consequences riding on that vote no matter where your loyalty is.”

North America correspondent Anthony Zurcher makes sense of the race for the White House in his twice weekly US Election Unspun newsletter. Readers in the UK can sign up here. Those outside the UK can sign up here.