The governor of Colorado, the first US state to legalize cannabis for recreational use, has said the decision of his voters was "reckless."
John Hickenlooper, a Democrat who is seeking re-election for a second term, was asked during a debate what he would say to other states considering similar measures.
He said: "I would view it as reckless before we see what the consequences are."
The governor added: "I think for us to do that without having all the data, there is not enough data, and to a certain extent you could say it was reckless.
"I'm not saying it was reckless because I'll get quoted everywhere, but if it was up to me I wouldn't have done it right? I opposed it from the very beginning. In matter of fact, all right what the hell, I'll say it was reckless."
Hickenlooper opposed the decision taken by voters in a ballot in November 2012 at the time.
The first licensed shops selling cannabis for recreational use opened in the state on Jan. 1.
The latest estimate from the state, arrived at last month, suggested it can expect to receive about $50 million (£31 million) a year in taxes levied on sales of the drug.
But Hickenlooper suggested other states should wait.
Alaska votes on whether to become the third US state, after Colorado and Washington state, to legalize recreational use in a ballot measure in November.
People in Washington, D.C., will also vote then on Initiative 71, which would legalize possession and home cultivation although not sales.