Herman Cain is engulfed in a firestorm of scandals this week - possible campaign finance irregularities and sexual harassment allegations – but the negative publicity has done little thus far to quell the GOP candidate’s popularity.

Cain’s campaign said it raised more than $400,000 Monday alone, in one of its best fundraising days. Since the scandal broke, the campaign says they have raised $1.2 million, nearly half of what they raised in the third quarter.

Meanwhile, his following on social media networks has surged. Since the story about the alleged sexual harassment broke Sunday, more than 12,000 people have joined Cain’s Facebook page, “Cain’s most significant growth spurt on Facebook in the last several months,” according to consulting firm OhMyGov.

The former chief executive of Godfather’s Pizza has also picked up 6,000 new followers on Twitter. Since Sunday, his Twitter numbers have jumped nearly 5 percent, the analysis found.

“The fact Cain continues to add fans at faster-than-normal pace during the biggest negative story of his campaign so far is a sign that he might endure and keep the pressure on [Mitt] Romney,” according to the OhMyGov analysis.

In the polls, the GOP candidate, who once stood little chance of making it to the top of the pack, is neck and neck with establishment favorite Mitt Romney. Republican voters say they haven’t yet changed their mind about Cain. In an ABC News/Washington Post poll released today, more than half of potential Republican voters say the controversy is not serious, and fewer than a quarter say it makes them less likely to support Cain.

Until recently, the former chief executive of Godfather’s Pizza was a virtual unknown inside and outside Washington. He has never held a public office and has failed in multiple attempts to run for one.

In 2000, Cain didn’t even make it as far as the primaries when he attempted to run for the Republican presidential nomination. He proved to be a more formidable challenger in the GOP primaries for the 2004 Georgia Senate race, but lost to Rep. Johnny Isakson.

So what’s changed this time around?

Experts say Cain’s popularity reflects, in no small part, a dissatisfaction with the GOP field and a desire on the part of voters to connect with someone who has a simple message they can understand. With his unconventional style, which he touts unabashedly, Cain’s appeal also lies in his not being a Washington insider.

Unlike 2000, primary voters are not looking for a candidate who will bring together the different factions of the Republican party – as they perceived George W. Bush to do – but a fresh face whose message will hold up against the president in 2012.

“There’s no single candidate who seems to be capturing the Republican primary voter,” Steinhorn said. “And Herman Cain has appealing communication qualities, a sense of directness, keeping policies simple, of not talking above the American people, of saying that he’s the no-nonsense type of guy who likes to get things done,” and “his unapologetic embrace of the Tea Party.”

Cain is also riding a wave that temporarily first lifted Rep. Michele Bachmann and then Gov. Rick Perry, also Tea Party favorites. Both candidates have since dropped to the bottom in polls. Some analysts predict the conservatives’ love affair with Cain - scandal or no scandal - likely won’t last long.

“People cycle through the alternatives. I think he’s benefiting from the overall perception of the field this time,” said Fred Boehmke, associate professor of political science at the University of Iowa. “My guess would he that you’ll probably see that start to decline.”

Cain, for his part, argues that this is just the beginning and attributes his success to grassroots support.

“That’s why this ‘flavor of the week ‘is now the ‘flavor of the month,’” the former businessman joked at an American Enterprise Institute event earlier this week. “And it still tastes good.”

It’s too soon to tell whether the controversies will hurt Cain. On the one hand, his supporters say they haven’t changed their mind about him, and blame the uproar on the media. But because Cain is still a candidate, he is more vulnerable to public opinion than officeholders who find themselves embroiled in a sex scandal, such as President Bill Clinton.

“Certainly, it will be seen that he’s not being candid and forthcoming if he’s trying to spin his way out of something,” said Leonard Steinhorn, a communications professor at American University. “It could call into question some of the character traits that people have projected on to him, and perhaps make them reconsider whether he is a candidate they should either support or consider.”

Cain needs to provide specific answers to the questions that are being raised, experts say, rather than play  the blame game, as he has done.

At the same time, the public assesses scandals on whether they indicate serious wrongdoing, not a trivial offense; whether they’re relevant to the individual’s official responsibilities; and whether they’re contemporaneous or at least reasonably recent, according to ABC News polling director  Gary Langer of Langer & Associates.

And, in this case, the public still has a lot more to learn about Cain.

“When you get a candidate from outside the political system, they bring a lot of energy and vitality, they don’t look and sound like everybody else,” said Ron Brownstein, National Journal Group’s editorial director. “But almost always, it means this is a candidate who has not been vetted in the same way as someone who’s run for office or held elected office has.”