Scott Walker stumbled on it during a trip to London. He and the rest of the 2016 Republican presidential field will face it repeatedly in the months ahead. So it would probably be best if GOP candidates prepared a quick and clear answer to the question, 'Do you believe in evolution?' They'll have to use it a lot.

If they are like most Americans, Republican candidates believe God has guided the creation of the Earth and its inhabitants. That alone is enough to craft an answer that will both represent their beliefs and work in a campaign.

The Gallup polling organization has done surveys about evolution for years. They ask this question:

Which of the following statements comes closest to your views on the origin and development of human beings: 1) Human beings have developed over millions of years from less advanced forms of life, but God guided this process; 2) Human beings have developed over millions of years from less advanced forms of life, but God had no part in this process; or 3) God created human beings pretty much in their present form at one time within the last 10,000 years or so.

In the most recent poll, done in May 2014, a plurality, 42 percent, said God created humans in their present form, while 31 percent said humans evolved with God's guidance. Just 19 percent said humans evolved with God playing no part in the process, and 8 percent had no opinion.

Looked at another way, 73 percent said they believe God has guided the creation of human beings. That's a pretty solid majority which undoubtedly includes a number of Democrats in addition to Republicans and independents. No matter their specific belief — young Earth creationists, intelligent designers, evolutionary creationists, whatever — the key element is God. Which means that a candidate should be able to say some version of the following when asked about evolution:

I believe God has guided the creation of Earth and all of us on it. There's a long scientific record of how life developed, and I don't see any conflict between that science and my own faith in God. I know some people believe humans evolved and God played no part in it. Of course I respect their beliefs, but God's role in our existence is a foundation of my faith. I believe He created us all.

It took a few hours, but Walker came around to something like that when, after the event in London at which he was blindsided by a question on evolution, he released a statement saying, "Both science and my faith dictate my belief that we are created by God. I believe faith and science are compatible, and go hand in hand."

Of course Republicans would be naïve to expect that will put an end to all questions. There will undoubtedly be questions designed to draw them into a detailed discussion of evolution and religion. A candidate will probably have a great majority of the public on his or her side if he shuts down those questions pretty quickly. The candidate could simply explain that there are lots of good people who have different opinions on this, and that for him, the key thing is believing that God guided our creation. Beyond that, it's not the role of the president of the United States to tell people what to believe about evolution.

Candidates can give that answer secure in the knowledge that, whatever some reporters might think, evolution simply isn't very important as a campaign issue. In 2007, Gallup asked whether a presidential candidate's views on evolution "are a legitimate indicator of whether he or she is qualified to be president," or whether those views "are not really relevant and therefore should not be discussed as part of the campaign." Seventy percent of respondents said a candidate's views on evolution are not really relevant, versus 25 percent who say they are a legitimate indicator.

Candidates should try not to alienate anyone in the positions they take. Where evolution is concerned, it's entirely possible to answer the question and at the same time avoid a problem — no matter how much some members of the press might want to stir things up.