Michele Leonhart, acting administrator of U.S. Drug Enforcement Administration, delivers a speech during a press conference at the International Drug Enforcement Conference, IDEC, in Rio de Janeiro, Tuesday, April 27, 2010. This yearâs conference theme of "Targeting the Facilitators" will focus on global drug trafficking organizations, precursor chemical control, the nexus between drugs and terrorism, financial facilitators, and intelligence sharing across multi-national law enforcement agencies. (AP Photo/Felipe Dana)

WASHINGTON -- The Senate could soon follow the House in banning the Drug Enforcement Administration from using its budget to crack down on states that have legalized marijuana for medical purposes.

Sen. Rand Paul (R-Ky.) on Wednesday introduced a Senate amendment to the Justice Department budget bill that would restrict DEA agents and federal prosecutors from using allotted funds to pursue providers of and patients using medical marijuana in the 22 states and the District of Columbia that have legalized its use.

The measure, if passed, would also protect states that have enacted the more limited legalization of CBD oil -- a non-psychoactive ingredient in marijuana that is frequently used to treat epilepsy -- for limited medical use or research.

Support for the ban is gaining momentum, as Sen. Cory Booker (D-N.J.) signed on Thursday as a co-sponsor of the Senate amendment, according to a statement from the Drug Policy Alliance.

“Poll after poll shows 70-80 percent of Americans support medical marijuana," Marijuana Policy Project's Dan Riffle said. "Even among conservatives, most oppose enforcement of federal marijuana laws in states where marijuana is legal for some purpose. Having two rising stars like Rand Paul and Cory Booker team up to introduce this amendment just shows how popular the issue has become, and that our outdated federal marijuana laws are inevitably going to change.”

Just last month, the House took even longtime supporters by surprise when it voted 219-189 for a similar amendment, co-sponsored by Reps. Dana Rohrabacher (R-Calif.) and Sam Farr (D-Calif.), that prevents federal agents from stopping the implementation of state medical marijuana laws. If both the Senate and House versions of the budget include the amendment, the final language of the budget bill is likely to include the ban when it emerges from a joint conference.

The DEA told HuffPost it does not comment on pending legislation.

"Our recent bipartisan victory in the House showed that elected officials are beginning to wake up to the fact that supermajorities of voters support letting states set their own marijuana laws without federal interference,” Marijuana Majority's Tom Angell told HuffPost. “Now that senators with clear presidential aspirations are getting on board, it's even more clear that savvy politicians are aware that this is a mainstream, winning issue they should support instead of run away from.”

Despite nearly half of all U.S. states having approved medical marijuana programs, the plant remains illegal under federal law. The DEA classifies marijuana as a Schedule I substance, along with heroin and LSD, with “no currently accepted medical use.”

During the Obama administration, the DEA and several U.S. attorneys have raided dispensaries that were acting in compliance with state laws. Those agencies have seemed less aggressive in their pursuit of medical marijuana providers in the 10 months since Deputy Attorney General James Cole issued a memo outlining specific federal priorities for marijuana enforcement.

Senate amendment text:

At the appropriate place in title II of division A, insert the following: Sec. __. None of the funds made available under this Act to the Department of Justice may be used, with respect to the States of Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Hawaii, Illinois, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Rhode Island, South Carolina, Tennessee, Utah, Vermont, Washington, and Wisconsin, to prevent such States from implementing their own State laws that authorize the use, distribution, possession, or cultivation of medical marijuana.