The field of candidates hoping to succeed retiring U.S. Rep. James P. Moran Jr. continues to take shape, as one prominent Arlington politician plans to jump into the race and another has ruled it out.

Moran’s surprise announcement last week set off a scramble among those eager to take the veteran Democrat’s Northern Virginia seat. A long list of current and former elected officials from Arlington County, Alexandria and Fairfax County put out word that they were mulling a campaign for the seat in the strongly ­Democratic-leaning district.

Del. Patrick A. Hope (D-Arlington) plans to announce Thursday that he is launching an exploratory committee, making him at least the second Democrat officially in.

Businessman Bruce Shuttleworth, who earned 26 percent of the vote against Moran in the 2012 Democratic primary, has said he is running again.

“We must have a proven progressive leader as our Democratic nominee in the 8th District,” Hope said in a statement. “We also need a nominee who will be ready to be effective on day one and able to build the necessary seniority that will be so crucial to our region.”

Hope has been in the news this week as the sponsor of a bill in the General Assembly that would prohibit the practice of “conversion therapy” by mental health professionals trying to “cure” minors of being gay.

Jay Fisette, the Democratic Arlington County Board chairman, made the opposite choice Wednesday, announcing that he is not interested in running for Congress.

He cited “the contrast between the dysfunctional climate on Capitol Hill and the can-do atmosphere in Arlington” as one reason for his decision against a campaign.

Other Democrats widely expected to run include state Sen. Adam P. Ebbin (Alexandria), Del. Charniele Herring (Alexandria), Del. Alfonso H. Lopez (Arlington) and Alexandria Mayor William D. Euille. A handful of other Democrats are at least considering a bid.

On the Republican side, former congressional aide Micah Edmond has entered the race.

President Obama won 68 percent of the vote in the 8th District in 2012.