Robert F. Kennedy Jr.'s exit from the Democratic Party (or was he booted out?) is only the latest sign that there are no more JFK Democrats left in positions of power in the Democratic Party.

        President John F. Kennedy was a staunch anti-communist who fought against union and government corruption. He was a pro-life Catholic. He was laser-focused on faster growth ("we can do bettah") and saw sweeping tax rate reductions as a step toward achieving 4% to 5% growth.

        Democrats are now for higher taxes: They ignore and excuse union and government corruption and they don't even talk about growth. It is all income redistribution.

        They should listen to the words of wisdom of JFK circa 1960 to 1963. In 1962, he famously declared: "It is a paradoxical truth that tax rates are too high and tax revenues are too low and the soundest way to raise the revenues in the long run is to cut the rates now."

        Sadly, today you could count on one hand the number of Democrats in Washington who believe that. JFK called for a reduction in income tax and capital gains taxes. Kamala Harris wants to raise every one of these rates -- including doubling capital gains taxes.

        Which brings me to RFK Jr. I don't agree with many of the positions that he takes, but he is right that the party undemocratically excised him from the ballot in many states. He is right about the incestuous relationship between big government and big business. 

        At a dinner party, I recently asked him about tax policy.

        "I learned from my uncle [JFK] that cutting taxes increases prosperity," he replied.

        Harris has never learned that lesson. She should take note. After the JFK tax cuts -- from as high as 90% to 70% and a 30% capital gains tax reduction by 30%, the economy boomed and tax revenues soared. The budget was balanced.

        Harris and my Democratic friends should educate themselves by reading Larry Kudlow and Brian Domitrovic's wonderful book, "JFK and the Reagan Revolution."

        That book also shows that tax revenues rose after the Reagan tax cuts, which were modeled after the JFK plan. What was remarkable about both these historical events is that the share of taxes paid by the rich rose after tax rates were cut. That was the "paradoxical truth" that JFK foresaw.

        JFK also was famous for talking about "a rising tide of prosperity to raise all boats." That's far different from the "soak the rich" message of Democrats today.

        RFK Jr. was right that he hasn't left the Democratic Party. The party has left him. And it has sadly left behind the policy legacy of his famous uncle -- who also would likely be a Republican today.

        Stephen Moore is a senior fellow at the Heritage Foundation and an economic advisor to Donald Trump. His latest book is: "Govzilla: How the Relentless Growth of Government Is Devouring Our Economy."