A White House event on Thursday will highlight a coalition of more than 20 grant makers that have pledged nearly $5-million over three years to help broaden the impact of the Social Innovation Fund, the new federal grant program for effective nonprofit groups.

The grant makers, which include big foundations like the Bill & Melinda Gates Foundation and the Atlantic Philanthropies along with venture-philanthropy groups like New Profit and SeaChange Capital Partners, are paying for an effort called “Scaling What Works.”

“The economic crisis reveals that even strong nonprofits with compelling evidence of their results struggle for capital,” said a statement by Kathleen P. Enright, president of Grantmakers for Effective Organizations, or GEO, the group that is operating the new program. She said the grant makers want to support the Social Innovation Fund’s goal of helping “result-driven programs” grow and better tackle the country’s social problems.

GEO said it would use the money to serve as a liaison between the philanthropy field and the government agencies involved with the $50-million Social Innovation Fund, increase the number of donors who will help promising nonprofit organizations expand and build up evidence of success, and help the grant-making organizations that receive the federal money share information about “lessons learned” among themselves and with others.

The White House announced yesterday that First Lady Michelle Obama and Patrick Corvington, chief executive of the Corporation for National and Community Service, will unveil on Thursday “philanthropic commitments” to bolster the Social Innovation Fund.