House Speaker Nancy Pelosi is gearing up for a vote this week on President Biden’s multi-trillion-dollar social welfare legislation, but strong divisions remain among Democrats over the size and scope of the final bill. Mrs. Pelosi told reporters Monday that she was eager to push through the legislation during an event at the White House commemorating Mr. Biden’s signing of the bipartisan infrastructure package. “I’m so happy that hopefully this week we will be passing Build Back Better [legislation] to get tax cuts to America’s working families, to create millions of more jobs, to lower health care costs, and all...