By Kristen Johanson

PHILADELPHIA (CBS) — The former political rival of a longtime Philadelphia congressman is expected to plead guilty Monday in what Feds call a ‘campaign debt pay-out scheme’ during the 2012 Democratic Congressional race.

Former Philadelphia Judge Jimmie Moore has been charged with one count of falsifying documents.

Prosecutors alledge Moore hid $90,000 given to him by Congressman Bob Brady’s campaign, to drop out of the race.

But Moore’s attorney says it’s simply a misfiling, and his client never tried to cover-up the funds.

He says Moore will plead guilty to the single charge, as part of Monday’s cooperating plea agreement, and will promise to testify to the truth if he’s ever called to the stand.

This summer, Moore’s former campaign aide, Carolyn Cavaness, admitted guilt to the same charge and is due to be sentenced in November.

A lawyer for Brady has said the longtime Congressman was buying polling information from Moore – a common practice in political elections.

Brady has maintained he’s done nothing wrong, and has not been charged.