Colorado lawmakers trying to regulate marijuana dispensaries are asking the U.S. attorney general to stop raids of medical marijuana operations.

The group e-mailed the request to Eric Holder on Monday, following up on a letter sent last week.

The lawmakers say the raids are discouraging dispensary operators and medical marijuana patients and growers from working with them on proposed regulations.

The letter was sent by Sens. Chris Romer and Nancy Spence and Reps. Tom Massey and Beth McCann.

A suburban Denver man has been charged with possession in federal court after agents raided his home and found 224 pot plants. Agents have also raided two laboratories that test medical marijuana after their owners applied for drug licenses.