Obama calls for end to gender pay gap

US President Barack Obama on Tuesday made an impassioned plea for equal pay for men and women in the workplace -- a gender gap that is far from being closed. "Equal pay for equal work should be a fundamental principle of our economy," Obama said on what he has designated National Equal Pay Day. It's a simple principle," he said at a ceremony dedicating a new national women's equality monument at a Washington home that once housed the National Woman's Party.