Women's rights groups, such as the National Organization for Women, have endorsed Sen. HIllary Clinton

In U.S. politics, there are mounting calls for Senator Hillary Clinton to end her campaign for the Democratic Party's presidential nomination. Mathematically, observers say Clinton cannot catch up with rival Senator Barack Obama in pledged delegates. And prominent Democratic Party officials fear that an acrimonious fight between Clinton and Obama could lead to depressed turnout among Democratic voters in the general election. But Clinton finds a strong defense from women's rights activists who do not want her to quit the race. VOA's Leta Hong Fincher has more.