U.S. Rep. Chaka Fattah, now facing public corruption charges, may soon have a third challenger in next spring's April 26 Democratic primary.

State Rep. Brian Sims on Thursday sent out invitations to a fund-raiser next week for the "Brian Sims for Congress Exploratory Committee."

The invitation asks donors to "Join Rep. Sims for a candid conversation about bringing ethical behavior back into Philadelphia Area Politics."

Gold sponsors for the Tuesday event are asked to contribute $2,700 – the maximum individual contribution allowed in federal election campaigns.

Sims, who represents Center City and parts of South Philadelphia, did not respond to a request for comment Thursday.

A Sims supporter, Brett Bunch, posted a picture of himself with Sims on Thursday morning on Facebook.

The caption: "So excited to spend this morning having breakfast with Brian and hearing him announce that he is running for U.S. Congress!!!!"

Bunch, a contract officer for the U.S. Department of Defense, later said he was one of about 15 people who gathered at the Rouge restaurant on Rittenhouse Square to hear Sims make his announcement.

Bunch said he first met Sims after moving to Philadelphia from Alabama last year. Sims was the first openly gay candidate to win a seat in the state House. Bunch said his approach to LGBT issues appealed to him.

"Frankly, coming from conservative Alabama, it was something I was very happy to find here in the area," he said.

Fattah, indicted in July, is fighting charges that include racketeering, bank fraud, bribery, and money laundering. He has pleaded not guilty and vowed to seek a 12th two-year term in office in the Second Congressional District, which covers parts of Philadelphia and Montgomery County.

Dan Muroff, a lawyer and Democratic leader of the Ninth Ward, declared his candidacy for the seat in August.

Lower Merion Township Commissioner Brian Gordon declared his candidacy last week.

The winner of the Democratic primary stands a good chance of taking the seat. Democrats make up 81 percent of the registered voters in the Second District, while Republicans are 8.5 percent and independents are 10 percent.

The long-running federal investigation and subsequent indictment have left Fattah politically vulnerable. A campaign-finance report filed July 15 showed that Fattah had $23,709 in the bank as of June 30, but had $61,558 in debts. The bulk of that debt was for legal fees.