Donald Trump's policy speech to the Detroit Economic Club stretched to nearly an hour. Yet Trump said not a word about two issues — Social Security and Medicare — that played prominent roles in speeches to the club by the last three Republicans to run for the White House: Mitt Romney, John McCain and George W. Bush.

Trump has often said that he will not cut or restructure the nation's two old-age safety net programs. "We'll ... save Social Security and Medicare without cuts," Trump said in a commercial last April.

At a GOP debate in February, Trump said, "We're not going to hurt the people who have been paying into Social Security their whole life, and then all of a sudden they're supposed to get less." He said similar things on a number of other occasions.

So when Trump took the stage in Detroit, there was a lot of talk about taxes, trade and regulation — and nothing about entitlements. Which might be a smart thing, at least politically. Romney and McCain promised entitlement reform and lost. Bush, who spoke in 2005 shortly after winning re-election, proposed Social Security reform and lost.

In addition, Romney even chose as his running mate the Republican lawmaker — Paul Ryan — most closely associated with entitlement reform, or entitlement cuts, as Democrats would call them. And here is what Romney said about entitlements in his 2012 Detroit Speech:

A few common-sense reforms will ensure we make good on our promises to today's seniors while saving Social Security and Medicare for future generations. Tax hikes are off the table, and there will be no change for those at or near retirement. But younger generations will enter a system strengthened for the 21st century.
When it comes to Social Security, we will slowly raise the retirement age. We will slow the growth in benefits for higher-income retirees.
When it comes to Medicare, tomorrow's seniors will have a choice among insurance providers, including traditional Medicare. As with Medicare Part D today, the private sector will compete to offer insurance coverage at the lowest possible price. Seniors will then receive government support to ensure they can afford that coverage. And with Medicare, like with Social Security, lower-income seniors will receive the most generous benefits.
Starting in 2022, new retirees will participate in this new system. We will gradually increase the Medicare eligibility age by one month each year. In the long run, the eligibility ages for both programs will be indexed to longevity so that they increase only as fast as life expectancy.
With these common-sense changes, we will have fixed our balance sheet. Instead of $62 trillion in unfunded commitments hanging over America's future, we'll have a balance sheet that is actually in balance.

In his 2008 speech, McCain included far fewer details, but left no doubt that if he were elected president, the two old-age programs would be in for big changes:

Politicians refuse to talk straight about Social Security and Medicare. The current Social Security system is unsustainable. Period. A half century ago, 16 American workers supported every retiree. Today, it's just three. Soon, it will be only two.
If we don't make some tough choices, Social Security and Medicare either won't be there for our children and grandchildren or we will have had to raise taxes so dramatically to support them that we will crush the prosperity of average Americans.
I will fight to save the future of Social Security and Medicare by reaching my hand across the aisle, but if the Democrats won't act, give me the responsibility and I will. If Congress won't act, I will demand an up or down vote on my plan. No problem is in more need of honesty than the looming insolvency of our entitlement programs.
No government program is the object of more political posturing and spin than Social Security and Medicare. Americans have the right to know the truth, no matter how bad it is. I won't leave office without doing everything I can to fix the fiscal problem that, more than any other, threatens our future prosperity and power.

Finally, in 2005, the newly-re-elected Bush chose to spend the "political capital" from his victory on reforming Social Security — a proposal that had not played a major role in his campaign. He outlined the plan in Detroit:

And to keep this country of ours competitive in the 21st century, we have got to honestly and openly address the structural problems of Social Security. In the last few days, I've traveled to North Dakota and Florida, and now to Michigan, to discuss my ideas and plans.
And I'm going to continue traveling. I'm going to spend a lot of time on this issue because I feel strongly that we better address it. And I'll tell you why.
I've reminded everybody I've spoke in front of that the Social Security system was one of the great moral successes of the 20th century, and I believe it was. And I assured them that today's seniors do not have a problem with Social Security. For those who have retired or are nearing retirement, born before 1950, the Social Security system is fiscally sound and will not change at all.
And that's an important message for our seniors to hear. You're in fine shape, and nothing is changing. But I warned every audience I've spoken in front of that the government has made promises to our younger workers that it cannot pay for. Social Security will go broke when some of our youngsters get ready to retire, and that's a fact.
And the whole world is watching to see whether or not we've got the courage to fix this problem. It's part of our structural deficit. Social Security means that we've got unfunded liabilities, debts that we owe to future generations that are going to be real hard to pay. And here's why.
Half a century ago, about 16 workers paid into the system for every one person drawing benefits. That's a nice, healthy contribution ratio — 16 to one. But today, it's 3.3 three workers to one. And over the next few decades, the numbers paying in for every beneficiary will be two to one — two workers for every beneficiary. But that's only half the problem.
The other problem is people like me, what they call baby boomers, are fixing to retire. And there's a lot of us. And not only are we fixing to retire, we're living longer, much longer than when the Social Security system was first designed. And not only that, the benefits that the government has promised are going up. They're increasing.
So think about it. With every passing year, you've got fewer workers who will be paying ever higher benefits to an ever larger number of retirees.
And that is the math. Thirteen years from now, in 2018, the Social Security system will be paying out more than it takes in. That's called being in the red. And every year afterwards, the problem gets worse. The shortfall is bigger than the year before.
So, for example, in the year 2027, the government will somehow have to come up with an extra — above and beyond the payroll taxes being collected — an extra $200 billion in that year alone to keep the system afloat. And in the year 2033, that shortfall will have grown to $300 billion. We got a problem. And it is plain to see. It is such a problem that in the year 2042, the system is going to be broke.
If you're a younger person, you ought to be asking members of Congress and the United States Senate and the president what you intend to do about it. If you see a train wreck coming, you ought to be saying, what are you going to do about it, Mr. Congressman, or Madam Congressman? Are you going to sit there and let the train run over workers, or are you going to act?
I'm calling upon the Congress to act.

Bush's proposal, of course, went nowhere — and he was working with a Republican House and Senate.

Trump's plan will face a lot of criticism from Democrats. Already, they are complaining that his tax cuts disproportionately benefit the rich. But unlike previous Republican standard-bearers Romney, McCain and Bush, Trump won't face the accusation that he is going to impoverish America's seniors, or, in the case of one memorable ad targeting Paul Ryan, to roll grandma off the cliff.

It's one third rail Trump has chosen not to touch.