Washington, D.C. ? Barack Obama raked in $40 million in March, leaving Hillary Rodham Clinton and her $20 million in the fundraising dust and stuffing his campaign treasury so he can outspend her in the crucial Pennsylvania primary.

His haul in new donations also buttressed his argument to Democratic superdelegates that he has built a vast network of donors and volunteers that they wouldn’t want to lose by denying him the nomination.

Obama has attracted nearly 1.3 million donors, largely through the Internet.

He has raised $131 million in just the first three months of this year to $70 million for Clinton.