LANSING, MI - A Democratic state lawmaker from Ann Arbor is ready to formally launch a bid to decriminalize possession of relatively small amounts of marijuana.

Rep. Jeff Irwin plans to formally announce his Michigan House legislation next week. It calls for making possession of one ounce or less of pot a civil infraction rather than a crime classified as a misdemeanor. That means the offense would carry a fine, but not the threat of jail time.

Other punishments – including for those related to intent to deliver or sell marijuana, or possession of more than one ounce – would not change.

At first blush, it would appear the bill faces long odds against passage in the Republican-led Legislature. Irwin acknowledges there are “some significant blockers that are going to make it very, very difficult to pass.”

Ari Adler, a spokesman for Republican House Speaker Jase Bolger, said the bill isn't going to be a priority.

"This may be a high issue for Rep. Irwin, but there are many other things facing Michigan that we need to deal with first," Adler said in an email. "Of course, if he was more willing to work with us on finding solutions for heavy issues, he might have a better chance of lighting up his 1-ounce initiatives."

But Irwin said there a number of lawmakers who support limited government and individual freedoms -- which could gain the bill some traction.

“I think that there is far more support than folks would initially think in the Legislature for this idea,” Irwin said.

Irwin says the government spends a lot of money trying to enforce prohibition of marijuana, and it obviously hasn’t worked.

“Marijuana has never been more available, and we do a terrible job of controlling it,” Irwin said. “By decriminalizing marijuana, we would take an important first step towards stopping the repeated failure that we’re engaging in with respect to marijuana prohibition.”

Supporters of decriminalizing marijuana say public opinion is swinging their way. Some are encouraged by the decision of Michigan voters in 2008 to allow marijuana for medical reasons. And some Michigan communities have approved local measures aimed at marijuana decriminalization, or making enforcement a low priority for law enforcement.

Some opponents of decriminalizing pot say it could increase the number of drug users and have negative consequences. They say decriminalization also could cause complications for citizens and police. Marijuana possession would remain illegal under federal law, for example.

Grand Rapids and Flint voters were among those approving marijuana decriminalization proposals in the 2012 election.

Email Tim Martin at tmartin4@mlive.com. Follow him on Twitter: @TimMartinMI