The potential certainly exist for FHA and VA loans. Also, some conventional loans if the buyer has a commission sales or compensation positions. Most lenders require a copy of the last two years taxes to be provided by the IRS. Since this office is closed the buyer could face a delay in their closing.
Both Veronica and myself posted some links to reference regarding the shut down and its possible affects on real estate. (See a couple threads down). Check those out for some good information.