Reps. Ron Paul (R-TX) and Barney Frank (D-MA) on Thursday called for the Obama administration to respect state marijuana laws, as California Gov. Jerry Brown (D) did on Sunday.

Voters in Colorado and Washington state both approved referenda legalizing the limited recreational use of marijuana. However, the federal Drug Enforcement Administration still classifies marijuana as a schedule I drug: the most restrictive classification, reserved drugs with a high potential for abuse and no accepted medicinal value.

"We urge you to respect the wishes of the voters of Colorado and Washington and refrain from federal prosecution of the inhabitants of those states who will be following their states’ laws with regard to the use of marijuana," Paul and Frank told the President in a letter (PDF).

"Respect for the rights of states to set policies on those matters that primarily affect their own residents argues for federal noninterference in this case, as does respect for the wishes of the voters – again, on matters that primarily affect those in the relevant electorate."

Eighteen states -- most recently Massachusetts -- and the District of Columbia have legalized medical marijuana. Though the current U.S. Department of Justice has held back on prosecuting medical marijuana patients, federal prosecutors have enlisted the help of the DEA and IRS to crack down on marijuana dispensaries in states were medical marijuana in legal.

With that precedent in mind, many supporters of drug policy reform fear the Obama administration will crack down on the new marijuana laws in Colorado and Washington state. The U.S. Department of Justice has yet to issue a statement on how it plans to proceed.

Last year, Paul and Frank introduced legislation that would remove criminal sanctions for the use of marijuana at the federal level. The bill would limit the federal government to enforcing cross-border or inter-state smuggling laws, and allow people to grow, possess, use or sell marijuana in states where it is legal to do so.