SAN DIEGO • The immigration issue has a magical power. It takes politicians

— in both parties — and shows us who they really are, as opposed to who they pretend to be.

If you’re an elected official, and you see immigrants and refugees as a threat to people like you, you’re going to try to keep them out.

On immigration, Democrats can be worse than Republicans. Give me Ronald Reagan and George W. Bush over Bill Clinton and Barack Obama any day of the week. And politicians in both parties have short memories.

Remember when Republicans like former Attorney General Jeff Sessions asserted the supremacy of the federal government? Once upon a time, they insisted that the U.S. Constitution gives Uncle Sam — and not “sanctuary states” like California — the right to sculpt immigration policy.

In the event that President Joe Biden doesn’t run for reelection, Vice President Kamala Harris is ready. She has skills, but she also has deficiencies. The immigration issue brings both to the surface.

On the positive side: Harris’ political adroitness is excellent, and her survival instincts are sharp. She knows how to promote herself and her life story, as she shapes a narrative that she’s “woke” enough to lead America to enlightenment and sensitivity in the 21st Century.

On the negative side: She has a thin skin, and she doesn’t take criticism well. Lately, she has lashed out at reporters when pressed about why someone tasked to solve the border crisis avoids visiting the border. This is more than just a GOP talking point. This week, a Texas Democrat — Rep. Henry Cuellar — also said Harris should visit the border to get a firsthand look at the problem.

Yet the vice president stubbornly refuses to budge. This has become a whole big thing. Now, if Harris eventually goes to the border, it’ll be a media spectacle rivaling former President Richard Nixon’s visit to China.

And when folks from Central America are fleeing violent gangs who threaten their sons and daughters, it’s not helpful for the vice president of the United States to callously tell them: “Do not come” because the administration will hold the line against “illegal migration.”

Who said anything about illegal? This lesson may have gotten past Harris in law school, but — as critics on the left pointed out — the process of would-be refugees coming to the U.S. to apply for asylum is 100% legal.

In an attempt to change the subject, Harris this week tried to put forth a kinder and gentler face. Pulling back from the right-wing and lurching toward the middle, she called on Congress to create a path to U.S. citizenship for the undocumented young people known as Dreamers.

Determined not to have her presidential ambitions squashed by the immigration issue, Harris is a moving target.