They’ve got to have it.

And we’re not talking about rabid Rick and Morty devotees storming McDonald’s in search of elusive Szechuan sauce.

This is about congressional Republicans and an insatiable appetite to approve tax reform -- preferably by the end of the year.

The prognosis? Publicly, everything is lollipops and rainbows.

Privately, even the most-earnest GOP tax-reform advocates are skeptical they can get this done -- at least soon. It’s the middle of October. There is no bill text. No specifics. Vague targets on corporate tax rates. Ambiguity on personal tax rates. Lots of buzzwords. Frameworks. Outlines. Principles.

House Republicans huddled for five hours a few weeks ago at Fort McNair, not far from the Capitol, to discuss the plan. Yet many came away grousing that they didn’t know much more than they did before the August recess.

“We’re making good progress on tax reform,” bragged the prospective author of the House’s tax reform package, Ways and Means Committee Chairman Kevin Brady, R-Texas. “I’m very pleased with the pace.”

It’s not uncommon to hear such platitudes from Brady and other leading Republicans. But a reporter then asked him for specifics on the “progress.” Brady provided very little.

“We’re continuing to make improvements every day,” he said, grinning.

Would the cuts be permanent?

“It is premature to identify which ones might be permanent,” Brady replied.

How about an agreement on eliminating state and local deductions?

“It just takes time to work through those options,” he said.

Oregon Sen. Ron Wyden is the top Democrat on the Senate Finance Committee. A few weeks ago, he found himself in the dark when it came to specifics.

“It reminds me of these old movie theaters when they would say there was a big movie,” Wyden mused. “They would say ‘Coming Soon! Coming Soon!’ But it never showed up.”

House Speaker Paul Ryan, R-Wis., insists tax reform is “coming soon.” And he even foretells when Congress must wrap this up.

“We’re going to keep people here for Christmas if we have to,” he said. “I mean, I don’t care. We’ve got to get this done. If we have to stay until Christmas, tough. We’ll do that.”

The “stay until Christmas” threat isn’t new from congressional leaders of either party.

Everyone knows that the real heavy lifting on Capitol Hill gets done around the holidays anyway. In December alone, lawmakers were already expected to tangle with a bill to avoid a government shutdown, deal with the young illegal immigrants known as “DREAMers,” stabilize health care markets, re-impose sanctions on Iran if the Trump administration totally nixes the nuclear pact with Tehran, perhaps lift the debt ceiling and approve additional installments to cover hurricanes and wildfires.

So Ryan’s threat just compounds an already vigorous schedule. Congressional signal-callers know that holding lawmakers hostage in Washington around the holidays often spurs results.

With big items on the agenda, members cannot dash home to trim the tree, go Christmas shopping or hang the lights. Keep them on Capitol Hill away from their families and lawmakers will pass something, anything, just to get out of town.

That doesn’t mean the end product is good. Consider that the Senate found itself in a similar bind in July -- desperate to approve anything on health care. That effort imploded spectacularly. Moreover, in February and March, Ryan presented the initial version of the House GOP’s health care bill as a “binary choice.”

Take it or leave it. Granted, the chamber finally approved such a bill in May. But a lack of support for the first bill forced Ryan to yank that proposal off the floor.

So, try the Christmas strategy.

Republicans are already reeling over the health care debacle. If they stumble on tax reform, Republicans risk looking as bad as the U.S. Men’s Soccer Team failing to qualify for the World Cup after losing to Trinidad and Tobago.

Tax reform faces three major enemies: parliamentary math, time and deficits.

Let’s start with parliamentary math.

The House now has 433 members -- 239 Republicans and 194 Democrats. That means Republicans can only lose 23 votes on their side of the aisle. The chamber recently adopted a budget as a special legislative prerequisite on tax reform. The GOP lost 18 of its own on that roll call tally alone. In other words, this is tight.

The Senate is another animal.

There are 52 Republicans and 48 senators who caucus with the Democrats. It takes two rounds of 60 votes to quash a filibuster on most legislation. There is no way Republicans can muscle through tax reform and overcome a filibuster -- even if they convince a few Democrats to play along.

Senate Republicans intend this week to approve a budget blueprint that can help them neutralize filibusters and just entail 51 votes to do about anything. But the Senate must first OK that budget.

The vote could be close. But there are some wild cards. Sen. Bob Menendez, D-N.J., has generally missed votes in the Senate due to his corruption trial in New Jersey.

That helps Republicans. Sen. Thad Cochran, R-Miss., has missed several weeks after a hospital stay. Cochran is due back this week. But his absence could boost Democrats.

Know this: if the Senate blunders in approving a budget, tax reform is dead because GOPers can’t overcome a filibuster.

Now, the time shortfall.

For a variety of reasons, Ryan is reluctant to push tax reform into 2018 -- an election year.

Tax reform is his touchstone issue. So for the speaker, it’s optimum to wrap this up in 2017. However, the House and Senate must take a little time to merge their respective budgets into one. That easily slides matter into November.

Brady says he won’t schedule a “markup” session (in which lawmakers actually write the bill) until there’s resolution on the budget issue. If Brady sets up a markup, it likely means he has the votes to advance the tax bill out of committee.

With these barriers, it’s easy to see how days drip off the calendar in November, through Thanksgiving and get you to, voila, Christmas.

Then there’s the deficit.

Republicans are confident that cutting taxes won’t bust the deficit. Those special budget rules, which enable GOPers to sidestep Senate filibusters, prohibit Congress from adding to the deficit over a 10-year period.

But rarely has Congress approved a bill under such rules that didn’t increase the deficit at the end of the 10-year window. Congress often puts “tough” spending decisions in the “out” years of such packages. The savings are never realized.

The national debt now stands at $20.38 trillion. Some economists and many lawmakers of both parties are skeptical that lower taxes can make up the difference in federal revenue via energized economic growth.

For years, Republicans extolled the virtues of “cutting spending” and eliminating deficits. There was barely a peep about deficits from House GOPers as they approved their budget two weeks ago. Some Republicans are starting to get antsy about how Congress is okaying nearly $52 billion in emergency disaster spending for the hurricanes and wildfires.

None of that spending was anticipated as recently as late August. None of the spending is offset.

Congress is asked to approve 12 annual spending bills each year to fund the government. The two disaster bills account for essentially a “13th” spending bill and a “14th” spending bill. Two or three additional disaster bills are likely in the coming months.

The first two emergency bills combined cost about the same as what Congress allotted for Commerce, Justice and Science programs (one of the spending bills) in fiscal 2016. This is almost $13 billion more than was allocated in fiscal 16 for the entire Department of Homeland Security and nearly $12 billion more than was appropriated for the State Department.

Of the 12 annual spending bills, the two emergency bills together are only smaller than the annual defense bill, the Labor/HHS bill, the Transportation/Housing bill and the Military Construction/VA bill.

Lawmakers don’t regret spending for natural disasters. But the deficit-reduction conversation has gone silent.

Why?

“We’ve come to the realization that we simply cannot cut,” conceded one conservative House Republican.

How’s that for honesty?

The question is whether those budgetary concerns are realized in opposition to the tax reform bill.

So not a lot is known right now on tax reform.

Earlier this year, Ryan argued strenuously for the inclusion of a “Border Adjustment Tax” or BAT, in the tax-reform package. Such a tax piles levies onto goods imported into the U.S. Ryan insisted on the BAT as a way to offset tax cuts and curb deficit spending. But President Trump never supported the plan.

A few weeks ago, Ryan and others held a splashy event at the Capitol to roll out general provisions of the tax reform plan but took no questions from reporters. As Ryan walked out, I hollered “What about the BAT?”

“I think you know the answer to that,” Ryan replied, prompting laughter.

No Border Adjustment Tax. And considering how vague everything else is, the lack of a BAT may be the only thing that’s settled in tax reform. But everything else is said to be “Coming Soon!”