Former Republican senator and 1996 presidential nominee Bob Dole has been diagnosed with stage IV lung cancer, he announced Thursday in a statement on Twitter. Dole, 97, represented Kansas in the Senate from 1969 to 1996, working his way up to Senate majority leader before resigning to unsuccessfully challenge Bill Clinton for the White House. “While I certainly have some hurdles ahead, I also know that I join millions of Americans who face significant challenges of their own,” Dole wrote in the statement. His treatment begins Wednesday, Dole wrote.