They are of different generations and from different Americas, their political lives separated by philosophy and circumstance, but on Monday at the White House, President Obama and former president George H.W. Bush and their families will unite under the banner of volunteerism.

At an afternoon ceremony in the East Room of the White House, Obama and Bush together will honor a retired couple from an Iowa farming town fittingly called Union, who have helped deliver free meals to hungry children around the world.

The couple, Floyd Hammer and Kathy Hamilton -- who founded their non-profit, Outreach, after seeing children die of malnutrition during a trip to Tanzania -- are the 5,000th winners of the Point of Light Award.

The award, established by Bush in 1989, celebrates the power of individuals to spark change and improve the world. Its name, like the Points of Light charitable foundation begun during Bush's presidency, is a reference to his 1989 inaugural address, in which he spoke of "a thousand points of light."

Obama has been a proponent of volunteerism as well, launching a National Day of Service connected to both of his inaugurations. And on Monday, a White House official said, Obama will announce a new federal task force to identify new ways that the government and the private sector can work together on national service projects.

Obama and Bush, who at 89 has been frail and battling health problems, will present the award together. First ladies Michelle Obama and Barbara Bush, as well as Neil Bush, one of the 41st president's sons and chairman of Points of Light, will be present. Prior to the ceremony, the two families will sit for a private lunch in the Red Room, a grand parlor on the first floor of the White House.

Monday's events mark a continued thawing of relations between Obama and the Bushes. Obama, a Democrat, swept into office in part as an indictment against former president George W. Bush and his Republican administration.

But in 2011, Obama warmly welcomed the Bush family to the White House as he awarded the Medal of Freedom -- the nation's highest civilian honor -- to the elder Bush, patriarch of an enduring political dynasty.

"His life is a testament that public service is a noble calling," Obama said of Bush. "Like the remarkable Barbara Bush, his humility and his decency reflects the very best of the American spirit. This is a gentleman."

While Obama and George W. Bush were traveling in Africa last month, they met in Tanzania, where Obama praised his predecessor's AIDS relief program.

Last week, Bush delivered a rare public address on policy matters and called on fellow Republicans to support comprehensive immigration reform -- the centerpiece of Obama's second-term domestic agenda.