The countdown to licensing the state’s first recreational pot shops is already well under way, applications are pouring in, and medical marijuana shops, of course, are already dispensing. Yet the businesses that service them — banks, insurance companies, accounting firms — are increasingly wary, and with good reason.

So it’s especially important for Congress to shake off its years-long slumber and pass a federal solution that will allow banks to handle funds from what is now largely a cash business — one from which the state expects to generate anywhere from $93 million to $172 million in taxes each year. Otherwise, Massachusetts pot shops and clinics might have to resort to stashing cash in a very large mattress.

This isn’t a problem that can fix itself — not with the growing list of states getting into the business of weed at some level; 29 states and the District of Columbia are already engaged in the sale of at least medical marijuana.

The decision by US Attorney General Jeff Sessions in January to rescind the so-called Cole memos sent a general shudder through the now burgeoning marijuana industry. The Obama era memos had urged federal law enforcement to exercise prosecutorial discretion in states that had legalized and were properly regulating medical marijuana.

But today, the Massachusetts Division of Banks notes on its website, “Financial institutions who are currently or considering serving the marijuana industry are urged to review this [Sessions] memorandum and all future pronouncements with counsel.’’

Just last month, Citizens Bank notified the Massachusetts Grower Advocacy Council — which itself neither grows nor sells marijuana — that its account was being closed. As a matter of policy the bank will not deal with the industry.

Century Bank, which took on cannabis industry clients assuming its state charter would provide a measure of protection, now finds itself caught up in a federal civil racketeering case brought by some of the Harvard Square neighbors of Healthy Pharms, a medical marijuana dispensary. The group, led by the Crimson Galeria, argue they have been “substantially injured by a conspiracy to sell marijuana near or next to their properties.’’ The will of the voters notwithstanding, they insist statewide licensing and permitting “directly conflict with the federal Controlled Substances Act.’’

Motions to dismiss the federal case are pending, but there is also no disputing the chilling effect on ancillary businesses. The whole thicket of dos and don’ts is, from a legal point of view, unsettled. Weed may be legal, marijuana tourism may be a real thing, but companies that actually “touch the plant’’ will find themselves still living on the margins — in search of banks, credit, insurance, and even someone to accept their ad dollars.

Senator Cory Gardner of Colorado last month announced with some fanfare that he had reached an agreement with President Trump “that he will support a federalism-based legislative solution to fix this states’ rights issue once and for all.’’

Senate minority leader Chuck Schumer chose 4/20 to announce his support for a bill to decriminalize marijuana by removing it from the federal Controlled Substances Act but to maintain a federal law enforcement role in preventing trafficking in those states that had not legalized pot for medical or recreational use.

In a recent editorial board meeting at the Globe, House minority leader Nancy Pelosi, who has supported that approach, didn’t seem overly optimistic that House Speaker Paul Ryan would spend his remaining months in office helping to make such a deal happen.

But with medical marijuana on the ballot this year in such unabashedly red states as Oklahoma and Utah, ignoring the issue is no longer an option — even for Republicans.

And make no mistake, it will take a bipartisan effort to find a way out of this federally engineered morass — sooner rather than later.