A Minnesota state senator and vocal advocate for fiscal conservatism failed to respond to a federal lawsuit alleging he failed to make payments on a $613,000 federal small business loan.

The U.S. Attorney's office moved Tuesday for a default judgment again Sen. Sean Nienow, R-Cambridge, and his wife Cynthia Nienow asking that he be ordered to pay back $748,584.14 for the loan principal and costs after he did not respond to the lawsuit filed Jan. 17. The Nienows borrowed the money for their now-defunct company, the National Camp Association, Inc.,as a gudance and referral service that helps families find camps for children, and provides other services like staff placement to camps.

The suit alleges that on Jan. 16, 2009, the U.S. Small Business Administration provided the loan, which was personally guaranteed by the Nienows. A copy of the signed guarantee is attached to the suit.

Nienow, 46, served in the state Senate from 2003 through 2006. After being defeated for re-election, he won back the seat in 2010, and won again in 2012. In the official directory of the state Legislature, he is described as a "consultant" with no additional details.

He did not respond to a message seeking comment.