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In a PARADE essay out Sunday on the meaning of fatherhood, President Obama says he has been an imperfect father and has suffered from missing out on his own dad.

In the essay titled, "We Need Fathers To Step Up," Obama acknowledges the impact on his life from the absence of his own father and reflects on mistakes he has made as a father.

"I have lost count of all the times, over the years, when the demands of work have taken me from the duties of fatherhood," he wrote. "There were many days out on the campaign trail when I felt like my family was a million miles away, and I knew I was missing moments of my daughters' lives that I'd never get back. It is a loss I will never fully accept."

The essay echoed a theme that Obama first revealed in a letter he wrote to his daughters two days before his inauguration. In the letter, which was also published in PARADE, Obama explained that he spent so much time away from them to run for president so they and every other American child can have a better life.

"I know that you've both had a lot of fun these last two years on the campaign trail," he said. "But I also know that it hasn't always been easy for you and Mom, and that as excited as you both are about that new puppy, it doesn't make up for all the time we've been apart. I know how much I've missed these past two years."

Obama encouraged his daughters to be selfless and pursue social justice.

"These are the things I want for you -- to grow up in a world with no limits on your dreams and no achievements beyond your reach, and to grow into compassionate, committed women who will help build that world," he wrote. "And I want every child to have the same chances to learn and dream and grow and thrive that you girls have. That's why I've taken our family on this great adventure."

In this weekend's essay, Obama explained how his father's absence made him realize the importance of fatherhood.

"I came to understand that the hole a man leaves when he abandons his responsibility to his children is one that no government can fill," he wrote. "We can do everything possible to provide good jobs and good schools and safe streets for our kids, but it will never be enough to fully make up the difference."

The essay is not the first time Obama has reflected on his father's absence. In his memoir, "Dreams from My Father," Obama said at the time of his father's death, he "remained a myth to me, both more and less than a man. He had left Hawaii back in 1963, when I was only two-years-old, so that as a child I knew him only through the stories that my mother and grandparents told."

Click here to read the PARADE essay.