WASHINGTON - US President Barack Obama says being a dad is sometimes his hardest job, but also the most rewarding.

Just ahead of Father's Day, Obama devoted his Saturday radio and Internet address to fatherhood.

Brazil's President Dilma Rousseff kisses Sasha Obama, as US President Barack Obama (L) introduces his daughters, upon their arrival at Palacio do Alvorada in Brasilia, Brazil March 19, 2011. [Photo/Agencies]

He talked about growing up without a dad, his own failings as a father and the values he hopes to teach his daughters Malia, 12, and Sasha, 10.

He described the responsibilities that all fathers have to their children and said his administration is trying to help during tough economic times and long deployments for US troops.

Obama spoke of helping to coach Sasha's basketball team. "In the end, that's what being a parent is all about - those precious moments with our children that fill us with pride and excitement for their future; the chances we have to set an example or offer a piece of advice; the opportunities to just be there and show them that we love them."

Obama, who was raised largely by his grandparents in Hawaii after his Kenyan father left when Obama was very young, also talked about what he wishes he'd done differently.

"I felt his absence. And I wonder what my life would have been like had he been a greater presence," Obama said.

"That's why I've tried so hard to be a good dad for my own children. I haven't always succeeded, of course - in the past, my job has kept me away from home more often than I liked, and the burden of raising two young girls would sometimes fall too heavily on Michelle."

Obama said he's learned that what children need most is their parents' time and a structure that instills self-discipline and responsibility, noting that even in the White House, Malia and Sasha do their chores and walk the dog.

"Above all, children need our unconditional love",' he said, "whether they succeed or make mistakes; when life is easy and when life is tough".