Help Needed on Citizenship Case Pending Background/Security Clearance

[pob6171]

Can anyone please please suggest how long does it take if the case is stuck in Background Check. I had my Interview 3 weeks ago, everything approved and the IO told me its pending Background/Security Check and I will have an answer in 2 weeks. No word from USCIS. Today I went for INFOPASS appt (Same DO) and they told me still pending security check and it can take from 3-4 months. Do anyone have any experience on normally how long it takes. Would writing/calling to Senators/Congressmen help possibly expedite the case. I would greatly appreciate any feedback from anyone with similar experience.
Thanks Indeed a million!