Senate Democrat leaders announced yesterday that they have reached agreement with the White House on key provisions of a $15 billion child-care bill, apparently clearing the way for passage of the legislation.

To reach agreement, the Democrats appeared to have accepted most of the changes demanded by the White House, including elimination or watering down of key education components such as an expansion of the Head Start program for preschool children and an after-school program for "latchkey" children. They also eliminated most of the proposed federal standards for child-care providers that early backers of the bill had advocated.

Senate Majority Leader George J. Mitchell (D-Maine) called the agreement "a solid bipartisan" proposal. He said the Senate would attempt to incorporate the measure into the deficit-reduction package now moving through Congress.

Rep. Thomas J. Downey (D-N.Y.), a key player in development of the legislation, called the agreement with the White House "a good step" but argued that it did not go far enough in dealing with the problems of preschool or latchkey children. "There's not enough for the middle class," he said.

Most of the $15 billion earmarked for child care in the next five years would be in the form of an earned-income tax credit aimed primarily at the poor. The credit would be paid for by continuing the telephone excise tax, which is estimated to bring in $13.1 billion over five years.

The balance of the money would be spent on various grant programs for the states. The Senate leaders and the White House agreed to a $2.5 billion program over the next three years, with money for the last two years to be negotiated later.