BALTIMORE — Investigators working to pinpoint the cause of Baltimore’s Francis Scott Key Bridge collapse discovered a loose cable that could have caused electrical issues on the Dali, the massive cargo ship that lost power and disastrously veered off course before striking the bridge.

When disconnected, the problematic cable triggered an electrical blackout on the ship similar to what happened as it approached the bridge on March 26, according to new documents released Wednesday by the National Transportation Safety Board.

The documents don’t include any analysis or conclusions, which will be released later in the board’s final report. A spokesperson for the board declined to comment as the investigation is ongoing.

The Dali was leaving Baltimore bound for Sri Lanka when its steering failed because of the power loss. It crashed into one of the bridge’s supporting columns, destroying the 1.6-mile span and killing six members of a roadwork crew.

Safety investigators released a preliminary report earlier this year that documented a series of power issues on the ship before and after its departure from Baltimore. But the new records offer more details about how its electrical system may have failed in the critical moments leading up to the deadly disaster.

The Dali first experienced a power outage when it was still docked in Baltimore. That was after a crew member mistakenly closed an exhaust damper while conducting maintenance, causing one of the ship’s diesel engines to stall, according to the earlier report. Crew members then made changes to the ship’s electrical configuration, switching from one transformer and breaker system — which had been in use for several months — to a second that was active upon its departure.

That second transformer and breaker system is where investigators found the loose cable, according to investigative reports.

Investigators also removed an electrical component from the same system for additional testing, according to a supplemental report released in June. They removed what is called a terminal block, which is used to connect electrical wires.

Engineers from Hyundai, the manufacturer of the ship’s electrical system, said the loose cable could create an open circuit and cause a breaker to open, according to a 41-page report detailing tests completed on the Dali in the weeks after the collapse. The engineers disconnected the cable as part of a simulation, which resulted in a blackout on the ship.

Hyundai sent engineers from its headquarters in South Korea to help with the investigation in April.

The new documents also included various certificates issued after inspections of the Dali pertaining to its general condition and compliance with maritime safety regulations.

“It’s pretty clear that they think they’ve found an issue that could cause a blackout,” said Tom Roth-Roffy, a former National Transportation Safety Board investigator who focused on maritime investigations. He said the loose cable was in a critical place within the electrical system.

He also noted that investigators have clearly taken a thorough approach and documented their findings well. The new documents suggest they found very few other problems as they combed through the various systems and machinery aboard the Dali.

In terms of whether the loose connection suggests inadequate maintenance of the ship or other problems with the crew, Roth-Roffy said it seems like a toss-up. Checking hundreds or thousands of wires is a tedious and time-consuming process, he said, and there are any number of factors that could cause connections to loosen over time, including the constant vibrations on a ship.

“To say that this should have been detected is probably true but somewhat unrealistic,” he said. “But the ship’s crew has ultimate responsibility for the proper maintenance and operation of the ship.”

The Dali left Baltimore for Virginia in late June. It was scheduled to undergo repairs there, and local media reported last week that it will sail to China, likely sometime later this month.

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Donald Trump has ruled out another presidential debate against Kamala Harris, two days after a showdown when the Republican former US president was rattled by his Democratic opponent.

In a lengthy post on his Truth Social platform on Thursday, Trump wrote there would be “NO THIRD DEBATE!” and insisted he “clearly won” Tuesday’s face-off with the vice-president in Philadelphia.

“When a prizefighter loses a fight, the first words out of his mouth are, ‘I WANT A REMATCH,’” he said on Truth Social. “KAMALA SHOULD FOCUS ON WHAT SHE SHOULD HAVE DONE DURING THE LAST ALMOST FOUR YEAR PERIOD.”

Shortly after Trump’s post was published, Harris took the stage at a campaign rally in Charlotte, North Carolina, where she told supporters that she wanted the chance to debate the former president again.

“I believe we owe it to the voters to have another debate because this election and what is at stake could not be more important,” Harris said in her first campaign trail appearance since Tuesday’s showdown.

With less than two months to go until the presidential election, Trump’s comments appear to eliminate the possibility of another televised debate between the two candidates.

Harris was widely seen to have won Tuesday’s presidential debate, which was viewed by more than 67mn Americans, according to Nielsen estimates. The event marked the first time Trump and Harris had ever met, let alone sparred on the issues.

In a back-and-forth that lasted about 90 minutes, Harris appeared to get under Trump’s skin as she questioned his stance on everything from abortion to foreign policy. At one point, after the vice-president cast doubt on the size of the crowds at Trump’s campaign rallies, the former president railed about the number of illegal migrants, rehashing an internet conspiracy theory that some were stealing people’s pets to eat them.

A CNN poll conducted by SSRS after the debate found 63 per cent of 605 people who watched it thought Harris had won, compared with 37 per cent for Trump. Before the debate, a panel of voters was split evenly at 50-50 on which candidate would perform better.

The Trump campaign has dismissed polls suggesting Harris had won the debate. “We found that despite the best efforts of Kamala Harris and [the] media to portray the debate as some kind of overwhelming win for her, voters did not see it this way as support for her remained flat,” Trump pollsters Tony Fabrizio and Travis Tunis said in a memo published on Thursday.

Harris’s appearance in North Carolina pointed to her campaign’s hopes that the state is now increasingly a target for the Democratic candidate. The Financial Times poll tracker shows Trump with a lead of less than a single percentage point, a significant narrowing of the margin since the vice-president replaced Joe Biden on the Democratic ticket.

Trump was expected to hold his own rally in Tucson, Arizona, another crucial swing state, later on Thursday. The latest polling puts him ahead of Harris by just over 1 percentage point in the state.

Meanwhile, the Harris campaign on Thursday said it had raised $47mn in the 24 hours after the debate. By comparison, the vice-president’s team pulled in about $36mn after she announced she had selected Tim Walz as her running mate.

The latest haul will build upon Harris’s sizeable money advantage: her campaign said it had $404mn in cash on hand at the end of August, compared to the Trump campaign’s $295mn.

In North Carolina on Thursday, Harris criticised Trump’s debate performance, saying: “I talked about issues that I know matter to families across America . . . but that’s not what we heard from Donald Trump.”

She laughed as she repeated the former president’s debate stage claim that he had “concepts of a plan” to replace the Affordable Care Act, more commonly known as Obamacare: “You heard what he said in the debate: he has no plan to replace it. He said ‘concepts of a plan’.”

Harris and Trump remain neck-and-neck in both national opinion polls and surveys of voters in swing states that are likely to determine the outcome of the election.