Mr. Rector estimates that the Senate bill would grant citizenship to between 9 million and 10 million illegal aliens. If allowed to become citizens, those immigrants would be permitted to bring their entire extended family, including any elderly parents. "The long-term cost of government benefits to the parents of 10 million recipients of amnesty could be $30 billion per year or more," Mr. Rector said. "In the long run, the [Hagel-Martinez] bill, if enacted, would be the largest expansion of the welfare state in 35 years." [Reform bill to double immigration,By Charles Hurt , Washington Times, May 15, 2006]
You can read the details of Rector's research here.