One of the reasons Mitt Romney and the GOP failed to get a convention bounce was their inability to talk tax cuts, economic growth, and jobs. In his 45-minute convention speech, Romney spent 200 words on the economy, with no mention of tax cuts. It was the same for his running mate Paul Ryan: no mention of tax cuts at the convention.

In fact, Romney and Ryan didn’t talk tax cuts leading up to the convention, and they didn’t in the weeks that followed. This has hurt them in the polls. They haven’t connected the dots between Obama’s anemic economy and the Romney-Ryan solution to improve it.

But, all of a sudden, there may have been an “aha” moment. In a “60 Minutes” interview this past Sunday, Romney did mention tax cuts, and take-home pay, too. Whoa.

“Take-home pay” is an old Reagan line. The Gipper appealed to middle-class voters who clearly understood that if you keep more of what you earn, and your take-home pay goes up, that’s the benefit of a tax cut.

Democrats like to hand out goodies by spending more and providing more government benefits. That’s the Obama story. But Republicans who win elections offer benefits to people through lower taxes.

In supply-side terms, rising take-home pay is an incentive for more work, investment, and risk-taking, since these activities pay more after tax, and because the free market will distribute the money, not the government central planners.

And Mitt Romney may be coming around to this view. Maybe it’s part of his strategy to “beef up” his message. On the side of his campaign bus it says “take-home pay and jobs.” Right on. And if Romney actually uses this language, he can put more meat on the bones by being more specific.

Basically, his 20 percent tax-reduction plan takes the top rate down from 35 to 28 percent. These are the big investors who help fund new businesses and job creation. And yes, as liberals always point out, their take-home pay will go up the most, by roughly $70,000 yearly.

But politically, Romney can speak directly to the middle class and show them how much their take-home pay will go up, too.

For example, a $70,000 middle-class family whose tax bracket falls from 15 to 12 percent will see a roughly $2,100 increase in take-home pay. That’s not nothing. Mortgage. Tuition. Car payments.

A married couple earning $143,000 whose tax rate under Romney drops from 25 to 20 percent will keep roughly $7,100 more in take-home pay. That’s good money. Or to use Obama’s middle-class benchmark, a married couple earning $220,000 a year whose rate drops from 28 to 22 percent will save over $12,000. That’s a big number.

That very term “take-home pay” has a middle-class feel to it. It’s something folks sitting around the kitchen table understand. Middle-class folks know what take-home pay means to their families.

So what I’m suggesting is that Romney put together specific examples of lower family tax rates and higher take-home pay. Specific examples. Put all those Harvard PhDs in the Boston headquarters to work. They can do it to the penny. I’m just roughing it out here in broad strokes, using work from my friends Jim Pethokoukis and Douglas Holtz-Eakin.

It’s really that simple. Talk up tax cuts and connect them to Main Street families in terms of the after-tax dollars and cents they understand. Higher take-home pay. More financial security. More jobs. Repeat these over and over. And then add meat to the bones.

For example, tell middle-class earners that their tax deductions will not be eliminated, or even limited. Reassure them. Take the Obama argument away: more take-home pay and no end to the child tax credit or other significant deductions.

And then circle back to the top tax rates, the Obama class-warfare tax rates, and say, “Look, in return for marginal tax-rate reduction, which will add investment and small-business incentives, we are going to limit and then eliminate a variety of tax deductions that you won’t need at the ultra-low 28 percent top rate.” If I were Governor Romney, I would mention a few, like the mortgage deduction, or the deductions for state and local taxes or interest-free municipal bonds.

And if Romney doesn’t want to go that far, he can state that all tax deductions are on the table in return for your lower tax rate. This is pro-growth. It’s fair. And it’s something most folks can understand.

The moral of this story is nice and simple: middle-class tax cuts, higher take-home pay, more prosperity, more jobs.

Reagan made it that clear. Romney can do the same.

Larry Kudlow is the host of CNBC’s “The Kudlow Report.”