WASHINGTON - Barack Obama, whose Kenyan father left his family when the future US president was 2 years old, said on Saturday he still thinks about how things would have worked out had his dad been there.

"I felt his absence. And I wonder what my life would have been like had he been a greater presence," Obama said in his weekly radio and Internet address a day before Father's Day in the United States.

The president said that being a father was "sometimes my hardest, but always my most rewarding job," and called on other fathers to make spending time with their kids a priority even when times are tough.

"And life is tough for a lot of Americans today. More and more kids grow up without a father figure. Others miss a father who's away serving his country in uniform. And even for those dads who are present in their children's lives, the recession has taken a harsh toll," he said.

Obama described a set of incentives by his administration on the website Fatherhood.gov to help fathers find fun things to do with their children and to connect better with them.

He also said every father needed to take responsibility "to do right by our kids."

"All of us can encourage our children to turn off the video games and pick up a book. All of us can pack a healthy lunch for our son, or go outside and play ball with our daughter. And all of us can teach our children the difference between right and wrong, and show them through our own example the value in treating one another as we wish to be treated," he said.

Obama discussed his father extensively in his 1995 memoir, "Dreams from My Father," which was republished after his political profile rose in 2004. His father died in 1982 in a car crash in Nairobi.

Acknowledging his political career had meant he was often away from home, putting more of the parenting burden on his wife, Michelle, Obama said he had tried to seize the most from the time he gets with his two daughters.

He also stressed he and Michelle had worked to install a sense of responsibility in the girls at their famous Washington address. "Malia and Sasha may live in the White House these days, but Michelle and I still make sure they finish their schoolwork, do their chores and walk the dog," he said.