It was a full house at the Pennsylvania 13 th District Democratic Forum today, but a key player was missing.

While three Democratic candidates for Congress were in attendance, front-runner and Clinton-in-law Marjorie Margolies was not present.

"Her campaign was contacted three times and asked whether or not she would like to appear. Her campaign declined," said Beverly Hahn, Montgomery County Democracy for America Chair. "I contacted Marjorie twice personally, she declined another two times, so I think after five times it was pretty clear that she and her campaign were not interested in coming to this forum. But it was not obviously because we didn't try to get her here."

The Margolies campaign did not return ABC News' request for comment, but Margolies did appear on MSNBC's "Disrupt with Karen Finney" later in the afternoon to discuss sexism in elections, where she referred to former Secretary of State Hillary Clinton as "Hillary."

The Pennsylvania 13th Congressional District Race Is Part Of ABC News' "14 for 14? Project: Check Out The Other Races

Candidates State Rep. Brendan Boyle, State Sen. Daylin Leach, and Dr. Valerie Arkoosh did attend, discussing issues from income inequality to NSA spying to marijuana legalization.

Boyle, who prides himself on a "100 percent pro-labor voting record," touted his 23 endorsements from Pennsylvania labor unions, and called himself a "champion for working families at a time like now when they need it most."

On NSA spying, Boyle proposed a specific idea to add a public advocate to FISA court proceedings, receiving applause from forum attendees.

"Having a public advocate in our … judicial system to take the other side, I believe, would keep the FISA Court honest."

Arkoosh, a practicing obstetric anesthesiologist, wove her experience as a doctor into her comments.

"I realized that the problems that we were facing were way beyond my ability to treat them in the exam room," she said, later noting, "The consequences of income inequality are something that I see every day in the people that I take care of."

Arkoosh, who has never held public office, also brought a physician's perspective to the issue of NSA surveillance.

"As a doctor, I know that at the core of every relationship between a doctor and a patient is privacy and trust that the information, often very sensitive information that's discussed between a doctor and a patient, will stay private," she said. "And I think as American citizens, we all have the right to believe that our government is going to handle our data with that same trust and security that we expect from our own physicians."

Leach, the most liberal of the candidates, told the story of being raised by his mother with the help of public assistance in Northeast Philadelphia, and later living with a series of foster families.

"The thing that saved me, the thing that gave me an opportunity to eventually have a career as a lawyer, a college professor, and as a small business owner, was the fact that my community invested in me," Leach said. "I'm running for Congress for many reasons, but at the core of it, I want to make sure the opportunities that were available to me are available to the next little boy who finds himself in a difficult set of circumstances."

Marijuana legalization proved to be the most contentious issue for the three Democrats.

Leach, who introduced a bill in Pennsylvania state legislature to legalize marijuana two weeks before he announced his candidacy, said he wanted to "stake my career on the idea that we need to have rational policies, even if it's controversial," calling the War on Drugs "completely irrational."

"I introduced the bill [in Pennsylvania state legislature] to legalize marijuana about two weeks before I announced I was running for Congress," Leach said. "I wanted to sort of stake my career on the idea that we need to have rational policies, even if it's controversial."

Boyle took a different perspective on the issue, deferring to the "laboratories of democracy" in Colorado and Washington.

"I think it's OK to sit back and keep an open mind about it," he said.

Arkoosh, meanwhile, toed the line as a physician.

"It's hard for me to get behind legalizing inhaling any burning substance into your lungs, but I want to be open, I want to see the data, I want to see the evidence, and I think that we can collect that and then make a decision," she said.

With no Republican contender, the May 20, 2014 Democratic Party primary will decide the likely winner of the 13 th District.