NEW YORK — With presidential candidates looking on, some 9/11 victims’ relatives appealed to them Wednesday for accountability as the U.S. marked an anniversary laced with election-season politics.

In a remarkable tableau, President Joe Biden, former President Donald Trump and Vice President Kamala Harris stood together at ground zero just hours after Trump and Harris faced off in their first-ever debate. Trump and Biden — the successor whose inauguration Trump skipped — shook hands, and former New York Mayor Michael Bloomberg appeared to facilitate a handshake between Harris and Trump.

Then the campaign rivals stood only a few feet (meters) apart, Biden and Bloomberg between them, as the hourslong reading of victims’ names began. At Trump’s side was his running mate, Sen. JD Vance.

The image was one of putting politics aside at this year’s solemn commemoration of the hijacked-plane attacks that killed nearly 3,000 people on Sept. 11, 2001. But some victims’ relatives, after reading out names, delivered political messages of their own.

“We are pleading for your help, but you ignore us,” Allison Walsh-DiMarzio said, directly challenging Trump and Harris to press Saudi Arabia about any official involvement in the attacks. Most of the 19 hijackers were Saudi, but the kingdom denies it was behind their plot.

“Which one of you will have the courage to be our hero? We deserve better,” Walsh-DiMarzio said. She’s a daughter of 9/11 victim Barbara P. Walsh, an administrative assistant.

Joanne Barbara was one of multiple readers who spoke out against a now-revoked plea deal that military prosecutors struck with alleged 9/11 mastermind Khalid Sheikh Mohammed and two fellow defendants.

“It has been 23 years, and the families deserve justice and accountability,” said the widow of Assistant Fire Chief Gerard A. Barbara.

Biden, on his last Sept. 11 in office, and Harris paid respects Wednesday at all three 9/11 attack sites: ground zero, the Pentagon and a rural part of Pennsylvania.

The president, vice president — and, separately, Trump — laid wreaths Wednesday afternoon at the Flight 93 National Memorial near Shanksville, Pennsylvania. Biden and Harris spoke with victims’ relatives and visited the local fire department; Trump and Vance went to a New York City firehouse earlier in the day.

The Flight 93 memorial stands where one of the hijacked planes crashed after crew members and passengers tried to storm the cockpit. Trump described the site as an “incredible place” in brief remarks from afar to reporters.

The attacks killed 2,977 people and left thousands of bereaved relatives and scarred survivors. The planes took down the World Trade Center’s twin towers and carved a gash in the Pentagon, the U.S. military headquarters, where Biden and Harris laid a red, white and blue wreath Wednesday afternoon.

While many Americans may not observe 9/11 anniversaries anymore, “the men and women of the Department of Defense remember,” Defense Secretary Lloyd Austin said earlier in the day.

The attacks altered U.S. foreign policy, domestic security practices and the mindset of many Americans who had not previously felt vulnerable to foreign extremists.

Effects rippled around the world. Victims came from more than 90 different countries, and the U.S. responded to the attacks with a ” Global War on Terrorism.” U.S.-led invasions of Afghanistan and Iraq killed hundreds of thousands of Afghans and Iraqis and thousands of American troops.

Communities around the country hold events on the anniversary, which Congress has titled both Patriot Day and a National Day of Service and Remembrance.

Thousands of Americans commemorate it with volunteer work — among them Harris’ running mate, Minnesota Gov. Tim Walz. He packed meals in St. Paul for people in need.

During early anniversaries at ground zero, presidents and other officeholders read poems, parts of the Declaration of Independence and other texts.