Soft-spoken Ben Carson catches up to GOP frontrunner Donald Trump in Iowa: poll
Secretary of Housing and Urban Development Ben Carson (AFP Photo/Mandel Ngan)

Retired neurosurgeon Ben Carson has drawn even with front-running billionaire Donald Trump in a poll in early-voting Iowa released Monday, as political outsiders surge in the US presidential race.

Real estate magnate Trump has spent weeks dominating the Republican field, and has emerged as a credible White House candidate for many voters in Iowa, the first crucible of the 2016 nominating contest.

But with Carson's stellar showing in a series of recent polls in Iowa and nationwide, and another survey showing Senator Bernie Sanders nipping at Democratic frontrunner Hillary Clinton's heels, the second-place candidates are exhibiting considerable power on the campaign trail.

Trump and Carson are deadlocked at 23 percent, according to the Monmouth University poll.

Only one other candidate polls in double digits: Another political novice -- former Hewlett-Packard boss Carly Fiorina, with 10 percent.

Senator Ted Cruz, Wisconsin Governor Scott Walker and former Florida governor Jeb Bush round out the top five.

"These results mark a significant shake-up in the leaderboard from Monmouth's Iowa poll taken before the first (Republican presidential) debate" in early August, said Monmouth University Polling Institute director Patrick Murray.

At that point, Walker, of neighboring Wisconsin, led the rankings.

The calm-demeanored Carson's favorability rating is sky-high at 81 percent to six percent, while Fiorina also shines at 67 to eight. Trump's favorability is 52-33.

Bush by comparison is deep underwater at 32-51 percent, according to Monmouth.

Carson, 63, is aiming to become the first African-American to win the Republican nomination.

He entered the nation's political consciousness two years ago with a speech criticizing President Barack Obama's policies in front of Obama himself.

Carson, who despite a childhood of "dire poverty" in Detroit, rose to become one of the nation's most respected medical professionals through his presidential campaign is seeking political "healing" and a renewed sense of compassion in America.

His campaign has been low-key compared to the braggadocious Trump, but Carson is seen as earning strong support from Christian conservatives, an important voting bloc in Iowa.

"Trump and Carson, one bombastic and the other sometimes soft-spoken, could hardly be more different in their outward presentations," according to respected pollster Ann Selzer, who released a Des Moines Register/Bloomberg poll of likely Iowa caucus-goers in late Saturday showing Trump leading with 23 percent and Carson second with 18 percent.

"Yet they're both finding traction because they don't seem like politicians and there's a strong demand for that right now."

Cruz and Walker are tied for third with eight percent in the Des Moines Register poll.

Bush and Senator Marco Rubio are next at six percent, while Fiorina earned five percent.

Shunning the political establishment is occurring to a degree on the Democratic side as well, according to the Register poll.

While results show Clinton ahead with 37 percent, she has lost one third of her support since May, while the liberal Sanders is now just seven points behind in the Democratic nomination race, at 30 percent.