Backdoor Roth Conversion: is loan offset rollover "deductible" or "non-deductible" contribution?

I'm seeking to convert a Traditional IRA to Roth IRA (backdoor Roth).  All of the contributions to the Traditional IRA were non-deductible due to income limits EXCEPT that it includes a loan offset rollover contribution (401k loan taken out, laid off, did a loan-offset rollover for the loan amount into the IRA).

Is the loan offset rollover amount "deductible" or "nondeductible" for conversion purposes?  Trying to calculate the pro-rata taxable amount since the account now includes investment gains that would be taxable, but don't know how to classify that loan offset contribution. 

Thank you for any thoughts you have.

The Rollover you did of the outstanding loan balance is not part of your basis.