Four members of the U.S. congress are banding together to protect the growing marijuana industry.

A bipartisan group of federal lawmakers launched the Congressional Cannabis Caucus in a press conference at the U.S. Capitol on Thursday afternoon. Republican congressmen Dana Rohrabacher (California) and Don Young (Alaska) joined Democrats Earl Blumenauer (Oregon) and Jared Polis (Colorado) to launch the new group. They are dedicated to developing policy reforms that can bridge the gap that currently exists between federal laws banning marijuana and the laws in an ever-growing number of states that have legalized it for medical or recreational purposes.

"We're stepping forward together to say we've got to make major changes in our country's attitude toward cannabis," Rep. Rohrabacher said at the start of the press conference. "And if we do, many people are going to live better lives, it's going to be better for our country, better for people, and it makes economic sense at a time when every penny must count for government."

Various polls show that a majority of Americans support legalizing marijuana in some form, and a strong showing in November's elections pushed the number of states that have legalized medical cannabis to 28, while another eight have voted for recreational legalization. (Notably, each of the four congressmen forming the Cannabis Caucus represent districts in states that have legalized both medical and recreational pot.)

In recent years, under President Barack Obama, federal law enforcement mostly left individual states alone to enact and enforce their own marijuana legislation. Three years ago, Congress passed a bill that prohibited the Justice Department from using federal funds to target cannabis operations that comply with local laws.

But the Trump administration has cast a cloud of uncertainty on a burgeoning legal marijuana industry that saw more than $6.5 billion in legal sales in the U.S. last year—a number that is estimated to reach $25 billion by 2020, according to market researcher GreenWave Advisors.

While Trump himself has publicly voiced his support for medical cannabis, specifically, some questions remain about how his administration will treat states that have legalized the drug in any form. Perhaps the largest reason for concern in the marijuana industry is the fact that Trump's recently-confirmed Attorney General, Alabama Senator Jeff Sessions, has a long history of opposition to cannabis legalization. In a confirmation hearing last month, Sessions was cagey when questioned about whether he would instruct the Justice Department to enforce federal laws that criminalize marijuana in states that have voted to legalize the drug. "It's not so much the attorney general's job to decide what laws to enforce," Sessions said at the time. The White House later indicated that Sessions would follow Trump's lead on the issue.

Several of the marijuana industry's top leading lobbying groups and associations—including NORML, the Marijuana Policy Project, and the Drug Policy Alliance, among others—issued a joint statement on Thursday commending the lawmakers for forming the Congressional Cannabis Caucus. Their statement read, in part: "We commend Representatives Blumenauer, Rohrabacher, Polis, and Young for their leadership on the issue of cannabis policy. The establishment of a Cannabis Caucus will allow members from both parties, who represent diverse constituencies from around the country, to join together for the purpose of advancing sensible cannabis policy reform."