26 U.S.C. § 271: Debts owed by political parties, etc.

In the case of a taxpayer (other than a bank as defined in section 581) no deduction shall be allowed under section 166 (relating to bad debts) or under section 165(g) (relating to worthlessness of securities) by reason of the worthlessness of any debt owed by a political party. a political party; a national, State, or local committee of a political party; or a committee, association, or organization which accepts contributions or makes expenditures for the purpose of influencing or attempting to influence the election of presidential or vice-presidential electors or of any individual whose name is presented for election to any Federal, State, or local elective public office, whether or not such individual is elected. For purposes of paragraph (1)(C), the term “contributions” includes a gift, subscription, loan, advance, or deposit, of money, or anything of value, and includes a contract, promise, or agreement to make a contribution, whether or not legally enforceable. For purposes of paragraph (1)(C), the term “expenditures” includes a payment, distribution, loan, advance, deposit, or gift, of money, or anything of value, and includes a contract, promise, or agreement to make an expenditure, whether or not legally enforceable. for the taxable year in which such receivable accrued, more than 30 percent of all receivables which accrued in the ordinary course of the trades and businesses of the taxpayer were due from political parties, and the taxpayer made substantial continuing efforts to collect on the debt.