The campaign fund of San Diego mayoral candidate and state Assemblyman Nathan Fletcher, who last month left the Republican Party and proclaimed his political independence, today gave $5,000 to the Republican Party of San Diego County, which has endorsed his rival, San Diego city councilman Carl DeMaio.

The contribution was disclosed in a filing made by the Fletcher for Mayor 2012 campaign posted online earlier today by the California Secretary of State's office.

Was it a refund, a parting gift, or something else?

Politicians often trade money amongst their various campaign committees, but this appears to be a rare case of an independent giving to what is essentially a rival political party.

Local GOP chairman Tony Krvaric confirmed that the party had received the cash, but referred all other questions to the Fletcher camp.

Fletcher campaign aide Amy Thoma said she hadn't heard about the donation, but would get back to us with the details.

When she does, we'll update here.

Update: We've just talked to Thoma, who says that the contribution was made to settle a lawsuit filed in small claims court here by local Republicans against the Fletcher camp.

According to Thoma's account, an individual donor had pledged to make a contribution to the county GOP on Fletcher's behalf, but when the party endorsed DeMaio, the would-be contributor declined to turn over the money.

As a result the GOPers sued the Fletcher campaign to obtain the funds, she said.