"Senator Robert Joseph Dole died early this morning in his sleep. At his death, at age 98, he had served the United States of America faithfully for 79 years," according to a statement from his family.

He had announced in February that he was being treated for advanced lung cancer. President Joe Biden visited Dole shortly after learning of the diagnosis.

Biden on Sunday released a statement mourning Dole.

"Bob was an American statesman like few in our history. A war hero and among the greatest of the Greatest Generation. And to me, he was also a friend whom I could look to for trusted guidance, or a humorous line at just the right moment to settle frayed nerves," Biden said. "I will miss my friend. But I am grateful for the times we shared, and for the friendship Jill and I and our family have built with Liddy and the entire Dole family."