The decision to pursue a lease extension is supported by GSAR 570.405 due the government encountering unexpected delays outside of its control in acquiring replacement space. The use of the sole sourc... The decision to pursue a lease extension is supported by GSAR 570.405 due the government encountering unexpected delays outside of its control in acquiring replacement space. The use of the sole source authority is appropriate where it is determined that award to any other offeror would result in substantial duplication of costs to the Government that are not expected to be recovered through competition.