T. Denny Sanford is a tough person to say no to. Just ask his friends and acquaintances.

Sanford, a Sioux Falls businessman who kick-started a fundraising campaign for the Sioux Valley Children's Hospital with a $16 million donation and earlier this year topped it with a $400 million gift to Sioux Valley Hospitals & Health System — the largest gift ever to a U.S. healthcare organization — lately has been encouraging friends and associates to follow his example. The resulting "Sanford effect" has led to several million-dollar gifts for the new Sanford Children's Hospital, including $1 million gifts from NBA player and South Dakota native Mike Miller and his wife and from Dana Dykhouse, president and CEO of First Premier Bank, and his wife. Others on the $1 million list for the hospital include local constriction firm owners Henry and Eleanor Carlson, Jr.; Kerry, Donna and Amanda Boekelheide; Tom and Barv Everist; and Miles and Lisa Beacom.

Nor are people at lower giving levels immune from Sanford's influence. Sioux Falls lawyer and state Senate majority leader Dave Knudson and his wife, city councilwoman De Knudson, pledged $25,000 to the children's hospital, as did Sanford Health chief executive Kelby Krabbenhoft and his wife, Heidi. According to Sanford Health Foundation president Brian Mortenson, most of the children's hospital pledges will be given over a five-year period, and everything raised now will be placed in an endowment.

"When the person approaching you is asking for money," said Dave Knudson, who serves as Sanford's lawyer for local charitable contributions and has been chairman of the hospital's board of directors, "it's more likely a success if it's someone you know and admire."