The former vice president's decision is in line with a long-running tradition of presidential campaigns pausing ads on the anniversary of the terror attacks in New York, Washington, D.C., and rural Pennsylvania that killed nearly 3,000 Americans and injured tens-of-thousands more.

In 2016, when the top of both parties’ tickets featured New Yorkers, both Trump and Hillary Clinton’s campaigns confirmed to POLITICO they’d halt television ads for the anniversary.

The precedent was first set by President George W. Bush and his Democratic opponent, John Kerry, in 2004. Then-Sens. Barack Obama and John McCain both paused ads in 2008 and jointly appeared in lower Manhattan, and Obama and Republican Mitt Romney suspended negative ads for the day in 2012.

Some campaigns have gone a step further to attempt to avoid any attempts of politicizing the day. In 2012, following an attack on an American compound in Benghazi, Libya, that resulted in the death of U.S. Ambassador Chris Stevens and other Americans serving there, the Romney campaign embargoed a statement on the attack until midnight.

But the day has not been totally devoid of politics, even in the election immediately following the attack. In 2004, Kerry issued a statement calling on the Bush administration to release a commission report on the intelligence community, to which the Bush campaign declined to respond until Sept. 12. An ad from Bush in 2004 also used imagery from the attacks.

The leaders of 9/11 Day — a nonprofit that encourages Americans to treat the anniversary of the attack as “a day of service and remembrance” — along with other organizations, sent a similar letter to Biden and Trump in late August asking the campaigns to “suspend political advertising, as well as campaign- or partisan-related appearances and social and traditional media activities on September 11, 2020, in favor of nonpartisan expressions of service, remembrance, unity and prayer.”

The letter noted that the moratorium has been “supported by all major party U.S. presidential candidates” since the attacks.

“I don’t believe we have received direct responses” from either campaign, said Jay Winuk, co-founder of 9/11 Day, saying he believed that has happened in the past as well. His brother, Glenn Winuk, was killed in Manhattan in 2001.

9/11 Day, which typically promotes a massive day of service, is pushing for a digital effort in light of the pandemic.

“Our view, as is the view of many in the 9/11 community … is that politicians have 364 other days of the year to express their different political views and do all the politicking," Winuk said. “On this one day, this one sacred day, let’s try to focus on the fact we’re all Americans and put the politicking aside.”