WASHINGTON — Donald Trump is planning to mark the 15th anniversary of the Sept. 11 terror attacks by attending the official commemoration at ground zero.

A person familiar with the decision said Trump is to attend the annual event Sunday at the World Trade Center site.

His Democratic opponent, Hillary Clinton, is also attending. It is not clear whether the two will cross paths, and neither candidate is expected to make public remarks.

Both Trump, a New Yorker, and Clinton, who was a US senator representing New York at the time of the attacks, have agreed to refrain from campaigning Sunday, continuing the tradition of setting aside partisan politics on the somber anniversary.

On Saturday, Trump told mourners at a funeral service for conservative leader Phyllis Schlafly that she promoted the idea that the ‘‘little person’’ can beat ‘‘the rigged system.’’

Trump spoke at the Cathedral Basilica of St. Louis, where he said Schlafly is looking down on those gathered, telling them to ‘‘keep up the fight.’’

The Republican nominee said Schlafly was ‘‘there for me when it was not at all fashionable.’’ Trump concluded his brief remarks speaking to Schlafly, saying, ‘‘We will never, ever let you down.’’

In other news, on Friday, Trump’s running mate Mike Pence, governor of Indiana, released a decade’s worth of tax returns, roughly a month after promising to do so. The campaign said Pence paid a state and federal tax rate that ranged between 10 percent and 16 percent over the past decade.

An analysis of just his federal taxes shows he paid an effective rate since 2006 that ranges between 6.4 and 12 percent, based on his family’s adjusted gross income.

Pence’s income topped out at $187,000 while he was still a member of Congress, but dropped to $113,000 last year. The family has donated 10 percent of their take-home pay to charity, the campaign said, which reflects an average 7.4 percent of their adjusted gross income.

Major-party presidential nominees have publicly released their taxes since 1976, but Trump is the exception. He has said he is waiting for the conclusion of an audit.

Last month, Clinton released her 2015 tax return, adding to the records dating to 1977 she had made public. Her running mate, Virginia Senator Tim Kaine, also released 10 years of tax returns last month.