Former President George W. Bush is set to headline a luncheon fundraiser for the Jeb Bush presidential campaign in New York on Sept. 10, according to several people familiar with the event, part of an expanding role he is playing to help raise money for his younger brother's White House bid.

The 43rd president is scheduled to take part in a retreat for top donors in Houston in late October that will also feature their parents, former president George H.W. Bush and former first lady Barbara Bush. Other finance events are in the works, including discussions about a fundraiser in Arkansas in early October, according to people familiar with the plans.

"It's no secret that President Bush is all in for Jeb, and he's proud to help by participating in fundraisers across the country as his schedule permits," Freddy Ford, a spokesman for George W. Bush, said in a statement.

In a fundraising appeal that went out to Bush supporters this week, the former president wrote that "I rarely send emails like this, but I wanted to make sure I asked for your support on behalf of my brother, Jeb."

"This is a consequential time in our nation's history, and we need a strong leader," he added.

The New York luncheon that George W. Bush is headlining was originally set to take place on Sept. 8 but had to be rescheduled for Sept. 10, putting the former president in the city the day before the 14th anniversary of the 9/11 terrorist attacks. He is not expected to remain in New York, however, having already committed to a participate in a commemoration in Dallas that day.

The former president's stepped-up presence on the fundraising circuit comes after he indicated earlier this year that he planned to steer clear of the 2016 race, saying he did not want to fuel an anti-dynastic backlash. Dealing with his legacy has proven to be a complicated political challenge for Jeb Bush, who has sought to carve out his own identity without criticizing his brother.  The two have yet to campaign publicly together.