WASHINGTON (AP) - President Joe Biden and Sen. Joe Manchin are said to be sharply divided over Democrats' huge social and environment bill, with the holdout senator pushing to erase the measure's improved child tax credit, as leaders' hopes of passing the legislation before Christmas appear to be fading away.The rocky status of their talks, described only on condition of anonymity by a person familiar with them, was among several indications that Senate Majority Leader Chuck Schumer faces a struggle to even begin debate on the massive measure before the holiday.