U.S. Rep. Chaka Fattah has vowed to fight the allegations lodged against him and four associates in an 85-page, 29-count corruption indictment, and he has said he will run for office again.

But if he were to resign, ward leaders within Philadelphia's Democratic Party get an outsize voice in replacing him in a special election. 

Before the election is held, both parties would nominate a candidate. In a regular election, candidates are nominated through primary elections. That's not the case for special elections.

Because of some rather arcane Democratic Party rules, Councilwoman Marian Tasco would call a caucus of ward leaders who would vote for the nominee.

Tasco says that candidates would likely start campaigns targeting the ward leaders before the meeting. 

"There's a lot of discussion," Tasco said.

All of this assumes Fattah resigns. It's also possible that he won't resign. Unless he is convicted -- and because complex cases like this could be in the court system for years before trial - he could run again.

Fattah could face a primary from Democrats who see his indictment as an opening. It's possible that he would survive a primary because the events in the indictment have been rumored for years. 

Assuming he survives a primary and hasn't gone to trial, Fattah's ward is among the most heavily Democratic in the nation, so it's likely he would win re-election. 

Tasco, for her point, wouldn't speculate on whether Fattah would resign, but said as the case develops, it's likely that pressure could mount on him to step down. 

"The man's innocent until proven guilty," Tasco said. "He has a right to stay until he's convicted."