Washington - President Barack Obama says he looks forward to a time when girls are "astonished" that women once made less than men and a female had never occupied the Oval Office.Obama and other Democrats on Tuesday seized on Equal Pay Day, a symbolic event marking how much longer it takes a woman to earn as much as a man. Women still make on average 79 cents for every dollar men are paid.Obama dedicated a new national monument to women's equality and pushed Congress to pass legislation requiring employers to show pay disparity is not based on gender. He indicated that he's encouraged by movement toward full gender equality in many arenas including corporate boardrooms, professional sports and presidential politics.He said he wants women in the future "to be astonished that there was ever a time when women earned less than men for doing the same work. I want them to be astonished that there was ever a time when women were vastly outnumbered in the boardroom or in Congress, or there was ever a time when a woman had never sat in the Oval Office," he said. "I don't know how long it will take to get there, but I know we're getting closer to that day."The president has not endorsed a successor, but his comments are the latest in a series that suggest he's supporting Democrat Hillary Clinton, who would be the country's first female president if elected."If we truly value fairness then America should be a level playing field," the president said at the Sewall-Belmont House and Museum, the one-time home of the National Women's Party. It is now designated as Belmont-Paul Women's Equality National Monument.Members of the US women's soccer team recently filed a wage-discrimination complaint against US Soccer, and actress Jennifer Lawrence has spoken out about making less than her male co-stars.The Democrats' focus on equal pay comes amid a presidential campaign where the Republican front-runner, Donald Trump, has alienated many female voters with his comments.Republican women dispute the notion that "women's issues" are separate from any other issues.