You will not be charged as inadmissible [under INA 212(a)(6)(c)(ii)] because that section of the Immigration and Nationality Act only applies "for falsely representing yourself as a US citizen for the purpose of obtaining any benefit under the INA". However, that may affect you "good moral character" for naturalization purposes during the five year statutory period.
I suggest that you get help from an experienced immigration attorney.
Law Office of Luis A. Guerra (954) 434-5800. This answer is of a general nature and should not be relied upon as final, nor is it intended as legal advice.
This is a complicated area of the law and it depends upon if the claim to citizenship resulted in your receiving a benefit under the Immigration and Nationality Act. However, your fact pattern is not realy clear as you mention a denial, but then refer to expecting to get sworn-in on Monday morning. Consult with an experienced immigration attorney who can review the facts of your case and advise you how best to proceed.
Jeffrey A. Devore, Esq.
Board Certified Immigration Attorney
Devore Law Group, P.A.
2925 PGA Blvd., Suite 204
Palm Beach Gardens, FL 33410
Telephone: (561) 478-5353
Facsimile: (561) 478-2144