Republican candidates are flummoxed about how to deal with the perpetual insult machine that is Donald Trump: Most ignore him in hopes he will go away, while a few lash out at him. Yet he keeps rising in the polls.

Of course he does – because his opponents are treating him as if he were a conventional candidate, and not the schoolyard bully he has been acting like. There is nothing to be found in the Lee Atwater or Karl Rove playbook to handle Trump. His competitors would do better going to StopBullying.gov, the website for a Department of Health and Human Services public-service campaign.

Substitute “candidate” or “candidates” for each mention of “child,” “children” or “kids” on StopBullying.gov, and you see how Trump’s been mishandled:

“Bullying is unwanted, aggressive behavior among candidates that involves a real or perceived power imbalance. … Bullying includes actions such as making threats, spreading rumors, attacking someone physically or verbally, and excluding someone from a group on purpose.”

• Threats? “I’ve been very nice to you, although I could probably maybe not be based on the way you have treated me,” Trump said at the first debate to Fox News’ Megyn Kelly, who has reportedly received death threats from Trump supporters.

• Rumors? “I really don’t know,” Trump said when asked recently if President Obama was born in the U.S. Trump, who led the “birther” movement questioning Obama’s birth certificate, has also been peddling stories about the Mexican government sending rapists into America.

• Verbal attacks? “Look at that face! Would anyone vote for that? Can you imagine that, the face of our next president?!” Trump said of Carly Fiorina, the only woman in the Republican presidential contest.

• Exclusion? After Bobby Jindal tried to stand up to Trump’s bullying, Trump tweeted: “I only respond to people that register more than 1 percent in the polls.”

StopBullying.gov specifically tells bully spotters to look for inappropriate sexual comments (“blood coming out of her wherever”); taunting (Trump called rival Lindsey Graham an “idiot” before giving out the senator’s cellphone number to a crowd); and cyberbullying (twitter.com/realDonaldTrump).

StopBullying.gov helps us understand why the initial strategy of Jeb Bush and others to ignore Trump’s taunts was a failure: “Not saying anything could make it worse for everyone. The candidate who is bullying will think it is OK to keep treating others that way.”

It also explains the folly in the strategy of those such as Jindal who answer Trump’s abuse in kind – the political equivalent of punching the bully in the face: “Only intervene if it feels safe to do so,” because fighting back “could get the candidate hurt.”

We also see how Ted Cruz has enabled Trump as one of the candidates who “may encourage the bullying behavior and occasionally join in.”

And we see what’s wrong with the responses by Fox News boss Roger Ailes, who has alternately scolded Trump and made peace with him, and Republican National Committee boss Reince Priebus, who went to Trump on bended knee to get him to pledge loyalty to the party: “When adults respond quickly and consistently to bullying behavior, they send the message that it is not acceptable.”

And the targets of Trump’s bullying? “Look at the candidate bullying you and tell him or her to stop in a calm, clear voice. You can also try to laugh it off.”

Bystanders and other adults – let’s apply the term loosely to supporters, party officials and journalists – have a role, too: Because “those who bully are encouraged by the attention that they receive from bystanders,” those who witness bullying can “blatantly state that they don’t think bullying is entertaining or funny,” and “commit to making it stop and consistently support the bullied candidate.”

I’m prepared to do my part. I haven’t called Trump a bully but rather, as StopBullying.gov suggests, “the candidate who bullied.” To label him a bully is to “send the message that the candidate’s behavior cannot change.” And I’d like to believe that everybody has the capacity for growth – even Trump.

Dana Milbank is a columnist for The Washington Post. He can be contacted at:

danamilbank@washpost.com