In this video framegrab from a May 17, 2012, video provided by Mother Jones Video, GOP presidential candidate Mitt Romney speaks at a $50,000-a-plate fundraiser in Florida. Romney told donors that 47 percent of Americans don't pay taxes and believe they are entitled to extensive government support. "My job is not to worry about those people," he said. (AP photo/Mother Jones video)

Big scoops come in small increments. It takes some luck and some connections, some phone calls and e-mails, and the time to build a relationship. Just ask David Corn.

Corn, the Washington bureau chief for Mother Jones magazine, on Monday wrote one of the most-talked-about stories of the 2012 presidential campaign about a video of Mitt Romney telling Republican donors at a May 17 fundraiser, among other things, that President Obama’s supporters constitute the “47 percent” of the nation who are “dependent upon the government, who believe that they are victims.”

Corn, 53, spent about four weeks coaxing the person who had surreptitiously shot the footage to hand over the full, undoctored video. It was recorded, apparently without Romney’s knowledge and via an unknown device, at the fundraiser at the home of a wealthy private-equity investor in Boca Raton, Fla.

In the end, Corn said, getting the story came down to trust.

“It takes time and a number of conversations between two people,” he said Tuesday, in one of a nearly nonstop series of interviews (“Dutch TV is waiting for me in my office!”). “As a journalist, you’re always worried about losing a scoop, by the fear that [a source] is talking to 25 other people. But you have to give it time and let the relationship develop.”

Follow President Obama, Mitt Romney, their running mates and spouses on the campaign trail

Corn, a liberal commentator on MSNBC, got a major assist from a freelance researcher, James Carter IV, who first found the snippet on YouTube. Carter suggested to Corn that there might be more in the full video held by the source. Carter, the grandson of the 39th president, also alerted the Huffington Post that a longer video might exist.

A race of sorts was on to get it.

Ultimately, Carter chose to work with Corn, with whom he had collaborated several months earlier on a Mother Jones story about Global-Tech Appliances, a Chinese company that allegedly had profited from the outsourcing of American jobs at a time when Romney’s company, Bain Capital, was investing in it during the late 1990s.

Carter, a left-leaning political researcher based in Atlanta, told reporters he stumbled across the video during a routine YouTube search. In interviews with television news shows and the Associated Press, he said he was especially glad to have unearthed the footage because Romney has frequently disparaged his grandfather’s presidency during the current campaign

“I’ve gotten a lot of Twitter messages from people supporting me and saying that it’s poetic justice that it was a Carter that uncovered this, considering the way that the Romney campaign has been talking about my grandfather,” Carter told AP. “I agree with that sentiment wholeheartedly.”

The younger Carter showed NBC an email he received from the former president about the video. The message read: “James: This is extraordinary. Congratulations! Papa”.

Through a series of private tweets and e-mails, Carter made contact with the source of the video last month. Corn then began a series of phone conversations with the source in an effort to persuade him to turn over the video and to reassure him that his anonymity would be protected.

At roughly the same time, Huffington Post Washington bureau chief Ryan Grim was doing his best to coax the source out of the shadows.

The source, whom Corn will only identify as a “he,” had apparently tried to provoke interest in the Romney recording by posting a brief clip, in which Romney describes the appalling conditions inside a Chinese factory, on YouTube shortly after the May 17 fundraiser.

In a further bid to attract attention, the source apparently posted links to some of the clips and anonymous comments about them in the message sections of Huffington Post and DailyKos, a liberal commentary site.

The source’s own postings — essentially audio files over distorted video images of the Boca Raton event — generated interest from several media sources, including the Huffington Post and BuzzFeed. But the disjointed, out-of-context quality of the clips, and the poor visual quality, made them curiosities rather than explosive revelations, Corn said.

The source “said he was afraid that he was doing something illegal and that he could possibly get sued by some very rich people,” Grim said Tuesday, adding, “both of which are legitimate fears” in view of Florida laws that prohibit the recording of anyone without their consent. Thus far, however, there are no indications that legal action is pending against the source.

Grim said the source told him that he decided to hand the video to Corn because he admired Corn’s story on Global-Tech. Corn may have been the ultimate victor in the race, but the Huffington Post beat Mother Jones to the punch Monday by posting a story and a short clip of the “47 percent” comment. However, Huffington Post didn’t have the full video that included Romney’s unguarded comments on a variety of issues, which Mother Jones posted a short time later.

Grim says he has no hard feelings: “Their story was better than ours, but ours was first,” Grim said. “David Corn is a great reporter. You win some, you lose some.”

Corn said there was no “strategic intent” in the timing of the full video’s release Monday afternoon, but there was one consideration: “We decided not to do it on the morning of Rosh Hashanah,” the Jewish new year, which fell on Monday. “We knew a lot of people in the media would be out of the office then, and we wanted maximum exposure. The morning of a holiday may not be a good time.”

As for the source’s identity, Grim is a little more forthcoming than Corn. “He’s not a [Democratic] party operative in any sense. My sense is he’s a progressive, firmly committed to progressive ideas. I don’t know if he’s an Obama supporter, but I can tell from his comments and commentary that he’s definitely on the progressive side.”

Neither Grim nor Corn will say so, but that suggests that the source wasn’t a Republican contributor and that he may have been at the Boca Raton event in some other capacity.