Republican leaders have a once-in-a-lifetime shot to dismantle Medicaid, a costly entitlement program that provides health care for the poor and the disabled.

In what other scenario could Speaker Paul Ryan and Senate Majority Leader Mitch McConnell find themselves working with a president so totally focused on the optics of “winning” in the short term and so utterly unconcerned about the real-life and political ramifications of taking benefits away from his own voters?

The last Republican president, George W. Bush, actually expanded Medicare entitlements. President Ronald Reagan worked with a Democratic Congress to stabilize Social Security, and President Richard Nixon oversaw a massive increase in eligibility for Medicare.

Over the years, legislators and presidents have nipped, tucked and tweaked the entitlement programs, but no one has ever gotten so close to a fundamental reversal of their structure as congressional Republicans are now. That is, Republicans have campaigned on reining in spending but they haven’t really had the chance to take the “entitlement” out of the three major entitlement programs.

Capping Medicaid

Now, they are positioned to do just that with Medicaid. Both the House-passed American Health Care Act and its sister legislation in the Senate would convert the program, in which health care costs are paid based on eligibility no matter the overall expense, to one in which benefits are capped for recipients. This is the plan dogmatic conservatives have been waiting for — and one many of them would like to replicate for Medicare in the future.

Four Republican senators—Rand Paul, Ted Cruz, Mike Lee and Ron Johnson — have said they are “not ready” to vote for the bill for a variety of reasons. None of those reasons appear to be that the changes to Medicaid are too much for them. If anything, they don’t like the bill because one of its other legs — the replacement of the Obamacare insurance subsidy program — tastes like a watered-down version of the original law.

You should expect that all four of them will vote for the bill if it looks like it’s going to pass. After all, when senators start talking about how they’re “not ready” to do something, they’re strongly suggesting that at some point they will do it. And they’ll never have as good an opportunity to reduce the long-term promises of the American government as they do now.

The real key to whether McConnell can get the 50 votes he needs (plus the tie-breaking ballot of Vice President Mike Pence) is a set of moderates with various concerns about the bill. But only one of them, Dean Heller of Nevada, is on the ballot in 2018. Heller said Friday he would not vote for the Senate bill in its current form. The others, including Susan Collins of Maine, Lisa Murkowski of Alaska and Rob Portman of Ohio, will have plenty of time to explain either yes or no votes.

It’s almost unthinkable that Republicans could lose the Senate over this issue in 2018. House Republicans are already on the hook with voters because they passed their version of the bill. And the president doesn’t really care much about the details of public policy.

Or a Sisyphean task?

It’s now or never for McConnell. And still, it’s an uphill battle to get even some fairly conservative Republican senators to vote for a bill that does harm to the most vulnerable in society while cutting taxes for investors.

Why? Because it’s not at all clear that the public has any real appetite for dismantling the social safety net. The poor and disabled are less politically potent than the retirees who make up the core of the Medicare and Social Security constituencies, but their welfare has been supported by generations of American voters and lawmakers.

There could be a backlash against Republicans who vote for this bill that is strong enough to affect the 2020 election — perhaps something akin to the Civil Rights Act turning the south Republican over the course of decades. Ryan and McConnell are playing with political fire, and McConnell, at least, seems to understand that. He’s never been as bullish about this approach as Ryan, whose bill was called “mean” by Trump — just weeks after Trump hailed it at a White House ceremony.

My gut tells me McConnell is ambivalent about enacting a repeal-and-replace law — that he might be OK with a defeat when the bill comes to the Senate floor later this week. Why else would he promise to vote on it whether it has the support to pass or not? He’ll be fine either way. If it fails, the senators who vote against it will be blamed individually by their base — but not for at least three years. If it passes, he’ll take credit for accomplishing a Herculean task. Not bringing to the floor would have been the most perilous outcome for McConnell personally.

Most congressional leaders, when faced with the question of whether to risk majorities to enact party priorities, choose to use their power to act rather than conserving their capital. Tom DeLay and Nancy Pelosi surely fit into that camp. But one reason McConnell has risen to the top and stayed there is that he tends to take a long view of preserving his own power and that of the GOP.

This week will reveal a lot about whether McConnell is willing to wield his power, and risk losing it, to adhere to conservative ideology. 

Roll Call columnist Jonathan Allen is a co-author of “Shattered: Inside Hillary Clinton’s Doomed Campaign” and has covered Congress, the White House and elections over the past 16 years.