(Erik De Castro/Reuters)

The day Donald Trump announced he was running for president, he proclaimed he would save Medicare — and I mean that literally. He would, he told us, “Save Medicare, Medicaid and Social Security without cuts.” He continued this line throughout the campaign. “We will not cut Medicare or Social Security benefits,” he told CNN at one point.

It was such an obvious con that the Trump campaign’s chief policy officer backtracked on the promise several months prior to the November 2016 election. “After the administration has been in place, then we will start to take a look at all of the programs, including entitlement programs like Social Security and Medicare,” he said.

And now, thanks to tax reform, we can see how Trump very well may go ahead and break that original promise — on Medicare, at least.

Earlier this week, the Congressional Budget Office released a statement  pointing out that if tax reform passes, Medicare will get whacked by up to $25 billion in 2018. That’s thanks to congressional rules that mandate cuts to programs including entitlements such as Medicare if a bill like the tax-reform legislation has the effect of increasing the budget deficit.

Of course, Republicans are denying that the CBO’s scenario will ever come to pass. “No such thing is going to be triggered automatically,” Republican Sen. Patrick J. Toomey (Pa.) told reporters on Tuesday afternoon.

But that sort of statement takes a lot for granted — in particular, that Congress would vote to override the Pay-As-You-Go rule, which mandates the cuts. Remember, the Senate is seeking to pass the tax-reform package under special rules that would allow it get through the chamber with a simple majority vote. But a reversal of the rules mandating the Medicare cuts would require 60 votes, one that would almost certainly take place after the tax reform passes (if it passes).

Republicans, perhaps, are hoping the Democrats will continue to be the party that frantically tries to clean up the mess they leave behind and will go along with them in undoing the cuts. Perhaps that will happen. But it’s more likely that the Republicans, once the cuts are in place, will be the party that refuses to go along. As Alan Rappeport wrote in the New York Times, “If Republicans decide to try to circumvent the pay-as-you go rule, it could be taken as a sign that they are not serious about deficit reduction.”

Now, of course, Republicans don’t really worry about deficits, at least when a Republican is in the White House. But they can’t simply say that. As a result, they could end up under intense pressure from the right not to undo the cuts, with little in the way of pushing back.

Indeed, the more likely outcome is that Republicans would want to seize on this as a way to make back-door cuts to Medicare. After all, Republicans have wanted to take the ax to Medicare — while calling it “reform” — for years. And they are still trying to do that right now. The Republican budget plan for fiscal year 2018, for example, contained provisions cutting the Medicare budget by almost $500 billion over the next decade. And the 2018 budget resolution initially passed by the House Budget Committee this past summer recommended increasing the age of eligibility for Medicare increase from 65 to 67.

Democrats and interest groups supporting the needs of older Americans are trying to get the word out about this week’s CBO news. “Taking $25 billion annually from Medicare to pay for tax cuts for wealthy corporations is an insult to every single hardworking American,” tweeted Massachusetts Rep. Joe Kennedy III on Tuesday. AARP and Indivisible are also pressuring Republicans to back off.

By the way, such cuts to the Medicare budget would mean Republicans are likely sticking it to many of the people who voted for them. According to the Pew Research Center, 53 percent of voters aged 65 and older preferred Trump vs. 45 percent who went for Hillary Clinton.

At some point, you’ve got to figure the elderly and near-elderly are going to figure out they weren’t in on Trump’s epic con, they were, like many others, the butt of it. It might not happen in time for to stop the Republicans’ turkey of a tax-reform plan, but we can expect the Democrats campaigning in 2018 to point it out again, and again and again. If tax reform passes, Trump’s broken promise will impact huge numbers of people — too many for it to slip by unnoticed.