Secretary Clinton:

You’ve prepared for this moment for your entire life. Your decades of experience, your knowledge of the issues, and your ability to hit the ground running on Day One make you eminently more qualified and capable than The Donald. He’s going to try to beat you on spectacle. You need to beat him on substance.

Read more: How Donald Trump Can Defeat Hillary Clinton in the First Debate

Your tone should be confident and prosecutorial, and your case is to prove that Trump is unfit for public office. But please don’t say it. Prove it. Your mission is to demonstrate that every time he talks on the global stage, his words could defile the office, embarrass the country and, yes, even provoke a war. Our polling couldn’t be clearer: If the election is a referendum on Trump, you win.

Remember this as he tries again and again to get under your skin: Trump is the most disliked candidate in modern history. Put him on trial. Rattle him. When he is challenged, he hits back. He loses control. He says dumb stuff. So push his buttons and compel him to reveal to the world that he is not qualified for the job.

So start with the sharpest, strongest contrast you have. At the Republican convention, Trump said, “I alone can fix it.” Your approach was much more popular: better together. Compare and contrast. Tell viewers what’s wrong before you tell them how to fix it. And please make a direct appeal, by name, to Republicans and Independents:

I know millions of people watching tonight are frustrated with Washington and with their government. They have every right to be frustrated. Our government isn’t working like it should because our democracy isn’t working the way it should. Donald Trump says he alone can fix it. That’s his approach, because everything is about him. I take a different approach. America is at its best when we are working together, not tearing each other down. If we are to be successful, if we are to ‘win again’ as Donald likes to say, it will require Democrats, Independents and Republicans to cooperate and compromise. There’s a lot that needs to be done, but it won’t happen with this hyper-partisanship or with insults. We need to grow up, act like adults, and remember that we work for the American people, not the other way around.

Your opening should then re-invoke the single biggest blunder of his post-convention campaign: his attack on the Gold Star Khan family. In my focus groups, nothing turned even his core supporters off more than his unforced, unfiltered attack on a family that is still grieving the loss of their war hero son. Put him on the spot, and ask him if he is ready to apologize:

Mr. Trump, in the front row is a family you know well, a family that has made the greatest sacrifice an American family can make—the loss of their son in the defense of their country. Their child is gone, yet you suggested that your sacrifices in life was as great as theirs. So I ask you, Mr. Trump. The Kahns are sitting in front of you. You’ve never apologized to the countless individuals you’ve personally insulted in your reckless, divisive campaign. Will you, tonight, apologize to the Khan family? America watched as you lashed out at them for no good reason. Would you like to set the record straight tonight, in front of the American people, and apologize for insulting them? Surely you’d agree that no one deserves your apology more than they do. And if you won’t apologize to this dignified, heroic family, will you apologize tonight to John McCain for disrespecting his years as a prisoner of war?” And if you won’t even apologize to McCain, is there any mistake you are prepared to acknowledge tonight?”

The second most damaging Trump trait is his affinity for dictators who are undoubtedly America’s adversaries. This weakness is compounded by his questionable business ties with Russia. As someone told us in a recent focus group, “He seems to like Putin a lot more than the world leaders who actually like us.” While this first debate is primarily about domestic issues, you have an unprecedented opportunity to appeal to national security voters who are alarmed by Trump’s behavior. I suggest the following language:

Mr. Trump, the American people are troubled by your repeated praise for adversaries who work every day to undermine America’s position in the world. You’ve complimented Kim Jong Un, the leader of the terrorist nuclear state of North Korea. You’ve said you respect Saddam Hussein because he was good at killing his enemies. And you’ve said that you like Putin because he likes you. I understand why you’d speak well of a Russian strongman, because you have business dealings there—dealings you refuse to disclose to the American people. But voters have the right to know: why are you repeatedly taking the side of the enemies of freedom—particularly the Russian regime that oppresses its people and jailed or assassinated its opponents?

Next, it’s time to force Trump to have his own Aleppo moment. Gary Johnson went from outsider darling to “disqualified for office” in about 30-seconds when he revealed he didn’t know that Aleppo was a key city in the Syrian civil war. That’s all it takes to kill a candidacy. You know Trump doesn’t know the details. You know that what you’ve learned last month is more than he’s learned in a lifetime. The strategic imperative is to focus on things that matter to people. For example:

Donald, you’ve said that we should have “taken the oil” from Middle Eastern countries in which we were militarily engaged or were hostile to America. Countries like Iraq, Iran, and Libya. So, a simple question: what is the name of the leader of Iraq? Iran? Libya? If you’re going to take their oil, by force, shouldn’t you at least know their names?

I’d take this one step further. He produced a list of judges he’d consider appointing to the Supreme Court. Ask him to name half of them. “These are your nominees. You told the world that they were the most qualified candidates for the Supreme Court. Who are they?” There’s no way he can—and that immediately undercuts his credibility and authenticity. Then bring it to a close:

Sound-bites and slogans do win elections. But this is more than an election. Knowing the facts in times of crisis is essential. Being president is the most important job in America … at one of the most important times in our nation’s history. Donald, these are countries that we have been at war with. American men have lost their lives. National security matters. The Supreme Court matters. The facts matter. Now is NOT the time to learn on the job.

The rules for these debates are going to encourage disagreement between the candidates. Assume that Trump is going to attack you early and often, and that the attacks will be more personal and insulting as you hold him accountable. I suggest using Ronald Reagan’s line from the 1980 debate. When he goes after you, just say, “As Ronald Reagan used to say, ‘there you go again.’” Then add: “Why do you feel the need to insult people just because they disagree with you? Is this how you will behave in the White House? Is this how you will talk to world leaders?” Make his temperament an issue.

But prosecuting Trump and holding him accountable is not enough. You won’t want to hear this, but even now, too many voters are not sure what you stand for or what you will fight for. On your website you talk about “an economy that works for everyone.” That’s not enough. You have to explain it in personal terms:

“Judge us by who we fight for. I am fighting for the people who live paycheck-to-paycheck, struggling to get by. I’m fighting for the people who work two jobs just to make ends meet. I’m fighting for the single mom who has to balance the needs of work with the needs of her family, and the mall business owner who wants a slice of the American Dream. You know who I’m fighting against? The multi-national companies who take their jobs and tax dollars from America. I have two words for the companies who outsource OUR jobs and OUR tax dollars. NO MORE. No more corporate tax dodgers. No more corporate tax cheats. If you want to do business in America, hire American workers. If you want to sell to American consumers, pay your fair share of taxes.”

Finally, Trump’s single greatest electoral weakness remains women. Nothing will differentiate you more effectively among women of all ages and all political allegiances than reminding viewers of what Trump as said and who he has said it to:

Mr. Trump, our children are watching. The presidency isn’t just a job title. It is a pulpit. Parents hope—and expect—that America’s president will be a role model for their kids, and not an embarrassment to them. How can the mothers and daughters watching tonight trust that you won’t call a woman you disagree with a ‘slob’ or a ‘fat pig,’ or attack them because of how they look or sound? Carly Fiorina was a successful businesswoman, yet you said she doesn’t have the face of a president, and listening to her gives you a headache. Really? History judges us by our words. Is that the language Jefferson and Lincoln? Of Roosevelt or Reagan? Is that the language of a United States president? Really?

Secretary Clinton, these debates are your opportunity to put your attorney skills back on display for the American people. Your objective should be to put Donald Trump, and everything he has stood for, on trial. Just remember that your client is the American people.

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