News Analysis: U.S. presidential candidate Carson surging ahead to challenge Trump before Republican debate

U.S. Republican presidential front-runner and billionaire mogul Donald Trump is finally facing a real challenge from another candidate who is right on his heels.

Ben Carson, a medical doctor and Washington outsider who just weeks ago was seen as a lightweight, is surging ahead, and in one recent poll trails Trump by only four points -- within the margin of error and essentially putting the two candidates neck-to-neck.

The bombastic Trump is riding a wave of populism and anti-establishment sentiment, as many Americans are fed up with Washington insiders that are perceived as out of touch with ordinary folks and not representing the interests of the middle class.

Carson, an award-winning brain surgeon but with no political background or experience running a large organization, resonates for his status as a Washington outsider. His message is a mix of traditional conservatism and anti-Washington views, yet delivered with far less braggadocio than the controversial Trump.

"(Carson) has obviously tapped into that outsider, anti-establishment, anti-politician thing that Trump has," Republican strategist Ford O'Connell told Xinhua. "But the difference here is he is very principled...and he's also got a likability right now that's over 70 percent that's basically worth its weight in gold."

"His whole spin is that being soft-spoken is a strength and not a weakness," he said, but adding that in a general election against the Democratic nominee, his subtlety may be a strike against him, if he were the Republican nominee.

The next Republican debate, which is slated for Wednesday, will likely be more important for Carson than for the other candidates, O'Connell said. "Here's someone who's surging and we're going to find out whether, after the next debate, he is just (a fad) or a very serious candidate."

"He's been far more durable than any of us would have thought. He and Trump, in terms of durability, I think have turned conventional political wisdom on its head," O'Connell said.

Still, while Carson has been a successful neurosurgeon, he has never managed a large organization or business and has never held public office.

"It's something that Carson is going to have to react to and find a way to overcome," O'Connell said, adding that Republican primary voters generally prefer people who have run organizations or held political office.

On policy, Carson differs from Trump on a number of fronts. Carson favors the idea of allowing illegal migrants to become guest workers, while Trump wants to deport 11 million illegal workers (most of whom come from Latin America). Carson earlier questioned the costs of such an initiative, such as the legal, logistics and law enforcement costs, which experts said could be astronomical if Trump's vision of simply rounding up and booting out illegal immigrants is realized.

"Carson has many of Trump's virtues without the bluster and rude comments. He is a nicer version of Donald Trump," Brookings Institution's senior fellow Darrell West told Xinhua.

"The two agree on a number of issues and each comes from outside the political class. That gives them special credibility with voters angry with the status quo and looking for someone from outside of Washington D.C.," West said.

"Neither has run for office before, which means they are not tarnished by politics. Carson has gained because people like a candidate from outside the typical political circles but who is nicer than Trump and far less likely to insult his fellow candidates," he said, adding that Carson is a serious candidate who should attract a lot of attention at Wednesday night's debate. Endi