Carson also told CNN's Jake Tapper on "The Lead" that the real estate mogul should apologize for insinuating that President Barack Obama was not born in the US and that a recent controversy over a contribution Trump made to the current Florida attorney general did not undermine his criticism of Hillary Clinton's ethics record.
Carson, commenting on Trump's apparent openness to a path for legal status for undocumented immigrants -- a proposal voiced by many of Trump's primary foes -- told Tapper that Trump needed to present "rational and workable plans" to the general electorate.
"Well, it's relatively irrelevant at this point because it is what it is," Carson told Tapper. "He is the nominee and has to come up with rational and workable plans, has to work with various advisers and experts in terms of the best way to do this and it needs to be done in a fair and compassionate way that is consistent with the way we in America do things."
When Tapper pushed back on Carson's argument that promises made to voters were irrelevant, Carson said campaign policies were often refined once a candidate took office.
"Well, I didn't say that they were irrelevant but bear in mind, what you talk about during a campaign and what actually happens, as you know, in all administrations are different," Carson responded. "You get different information, you learn things along the way, and you make adjustments along the way."
Carson added: "Perhaps there were others who had already learned those things. It doesn't matter. The important thing is that it does get learned and it does get integrated into the process of decision-making."
Carson denied that Trump's shift to policies similar to his Republican opponents undermined the sincerity of his campaign promises.
"Well, very much like the promises that have been made to people in our inner cities for decades and yet their condition is not getting any better," Carson said. "Those matter too."
Carson said Trump's appeal among African-American voters could be improved if the real estate mogul apologized for his persistent claims that Obama was not born in the US.
"I think that would be a good idea, absolutely," Carson told Tapper. "I suggest that on all sides."
Trump was a prominent mouthpiece for the "birther" conspiracy theory in 2011, leading the push for the Hawaiian-born Obama to release his birth certificate as proof that he was not born in Kenya. Asked about the so-called "birther" issue during a gaggle with reporters aboard his campaign plane Monday, Trump replied, "I don't talk about it."
"Let's get all of the, you know, the hate and rancor out of the way so that we can actually discuss the issues," Carson said, adding that both candidates should focus on issues such as the economy, national security, criminal justice reform and education.
Carson continued: "These are the big issues and how we get caught up in all this other stuff is a reason that we will go down the tubes if we don't correct it."
African-American voter outreach
But Carson said he was pleased Trump was engaging with voting blocs who usually support the Democratic Party, despite recent polls suggesting his efforts among non-white voters has so far been in vain.
"But wouldn't you agree, Jake, that it's better that he do some outreach?" Carson said. "You know, traditionally the Republicans have pretty much left the African-American vote to the Democrats and assumed that there was no point in even trying for it. He is at least making an effort and putting out some proposals that are actually pretty darn good, you know, in terms of school choice and school vouchers."
Carson accompanied Trump on his highly anticipated visit Saturday to Great Faith Ministries, a nondenominational church in Detroit, Trump's first major pitch made directly to the black community as a presidential candidate.
Carson added Trump's corporate tax reforms, however, would appeal to the entire electorate, not just voters in the country's inner cities.
"I think a lot of this stuff is not Democrat or Republican stuff. This is what works for America," Carson said. "And if our inner cities are not functioning at a high level, there is absolutely no way that our nation will succeed."
Carson shrugged off suggestions that a recent IRS fine against Trump for a donation he made to Florida's attorney general undermined his argument against Clinton's record at the State Department.
Trump recently paid the IRS $2,500 after he donated $25,000 to a group backing Pam Bondi while she was deciding to investigate Trump University over allegations of fraud. Meanwhile, Trump has accused Clinton of engaging in "pay-to-play" practices at the State Department involving donations to the Clinton Foundation.
"Pam Bondi is a very meticulous lawyer and would be looking very carefully at anything that looked askew," Carson told Tapper. "So I say if people want to investigate it, they certainly should, but it would not be consistent with what I know."
When Tapper informed Carson that Trump had already been fined by the IRS for making the donation using money from the Trump Foundation, Carson said he did not have a problem with Trump incurring the penalty if the contribution was in fact illegal.
"Well, you know that Donald Trump has admitted that he knows how the system works and that he has worked with both Democrats and Republicans and that money has been exchanged," Carson replied. "You know he's not tried to hide the fact that has occurred. A lot of times the rules become more clear after you've done something."