There is one candidate in the Republican presidential race who can potentially derail the Donald Trump Express, and it’s not Jeb Bush.

The Donald’s dominance in the GOP race so far has obscured the equally amazing rise of retired neurosurgeon Ben Carson. For weeks, Carson has been second, tied or even leading in the polls.

As the lone African-American in the race, he has been compared to Herman Cain, the black businessman who ran for the Republican nomination in 2012. In the autumn of 2011, Cain rose to lead in the polls. A sexual harassment scandal and several embarrassing interviews that exposed his lack of basic knowledge forced him to drop out. Like Cain, Carson has never held political office.

Carson may yet implode, but so far he has avoided any disabling scandals, and his ignorance of issues is presented more as an asset than a liability. On his campaign website, he leans toward broad statements rather than policy specifics.

However, when he has taken a position or voiced an unrehearsed opinion, his stance has been every bit as extreme as that of anyone else running. In expressing his opposition to the Affordable Care Act, where he first gained notoriety, he compared it to slavery. He fiercely opposes same-sex marriage and gay rights, opining that prisons turn people gay. He argues that President Barack Obama is anti-Semitic because he signed the Iran nuclear agreement.

Carson resonates with the same base of far-right Republican voters that Trump, Texas Sen. Ted Cruz and former Arkansas Gov. Mike Huckabee speak to, but he may have more staying power.

Carson’s favorability rating (68 percent) is the highest of all Republican candidates, while his unfavorability (14 percent) is the lowest, according to a recent Public Policy Polling survey. This compares with Trump’s ratings of 56 percent and 30 percent, respectively.

Carson also has the highest “second-choice” ranking, at 13 percent. This means when Huckabee, Louisiana Gov. Bobby Jindal and other low-polling, like-minded candidates eventually drop out, Carson is poised to pick up significant support.

Carson’s perch at the top of the polls demonstrates that it is not just Trump’s outsized celebrity, oversized ego and unorthodox campaign that have the billionaire stealing the show. Carson’s and Trump’s anti-immigration and anti-welfare-state ideology animate GOP voters.

However, Trump continually presses the white resentment button, which is highly problematic for a party needing voters of color to have a chance of winning the presidential race. Carson provides a symbol of diversity without ever addressing issues of racial justice.

Carson speaks a language that is unwaveringly white and conservative — and his supporters understand this.

Republican leaders have prayed for a Trump collapse and disappearance, believing that his winning the nomination would doom their chances for seizing the White House. The real issue for the GOP, however, is that neither of the party’s top two candidates is qualified to be president.