Chris Christie and Rand Paul, likely rivals in the 2016 GOP presidential race, have found a new wedge issue: weed. The question is whether or not to continue prosecuting the federal government's drug war. In a visit to the key presidential swing state of Colorado this week, New Jersey Governor Christie firmly portrayed himself as a hawk in that war -- even as new data show crime plummeting in Denver in the months after Colorado legalized recreational marijuana. A day after Christie's comments, Senator Paul proposed drug reform legislation that positions the Kentucky lawmaker as an opponent of the drug war.

During Christie's Wednesday trip to Denver, the federal-prosecutor-turned-governor stood by his earlier criticism of the state's voters for approving a law in 2012 that permits recreational marijuana use.

“What I said is what I believe," he told reporters who asked him about an April radio interview in which he slammed the new marijuana law. Ignoring data showing Colorado outranking New Jersey on many social and economic metrics, Christie said in that earlier interview that his state is a better place to live because of Colorado's legal weed.

"See if you want to live in a major city in Colorado, where there are head shops popping up on every corner, and people flying into your airport just to get high. To me, it's not the quality of life we want to have here in the state of New Jersey," he declared.

Christie's reiteration of that message this week follows his statement last month criticizing medicinal marijuana as "a front for legalization." By contrast, his prospective 2016 GOP rival, Paul, this week introduced an amendment to a jobs bill that would statutorily protect the right of states to "implement laws that authorize the use, distribution, possession, or cultivation of marijuana for medical use."

Pressed in Denver on Wednesday to explain his opposition to Colorado's legalization efforts, Christie said, "I think legalizing marijuana is the wrong thing to do from a societal perspective, from a governmental perspective.”

Some signs from the government, though, suggest otherwise.

For instance, Colorado's Joint Budget Committee reported in February that the state is now on track to collect $184 million in marijuana tax revenues in the first year and a half of legalization. Those revenues could grow if Congress enacts a House-passed bill designed to let the federal government help marijuana distributors access business banking services. With Colorado's new marijuana laws directing a significant chunk of cannabis revenue to education, legalization could help prevent the kind of major cuts to schools that Colorado endured in recent years.

Those new revenues might not be worth the trouble if drug warriors' fears came true and marijuana legalization was accompanied by a major crime wave. However, in the six months that marijuana has been legal, the Denver Police Department has reported a significant reduction in crime. According to police statistics comparing crime rates from the first six months of 2013, the city has seen a 3 percent overall drop in violent crimes. That includes a 38 percent drop in homicides and a 19 percent drop in sexual assaults. Additionally, the data show an 11 percent decline in property crimes during the same time.

Though both law enforcement officials and drug law reformers say it is too soon to attribute those crime reductions to marijuana legalization, the data are consistent with a March 2014 study by University of Texas researchers showing no connection between looser marijuana laws and crime increases. Analyzing crime data from 11 states that had legalized medicinal marijuana, they found "no evidence of increases" in violent crimes after the new drug laws had passed. In fact, the researchers found that the total number of violent crimes was lower for states legalizing medicinal marijuana, which they said suggests legalization "may have a crime-reducing effect."

To counter these findings, anti-drug groups such as Smart Approaches to Marijuana have warned that Colorado's move to legalize cannabis will come with unintended consequences.

"By any measure, the experience of Colorado has not been a good one unless you’re in the marijuana business," SAM spokesperson Kevin Sabet recently told the New York Times, citing sporadic episodes of children eating marijuana edibles and local sheriffs complaining about stoned drivers. "We’ve seen lives damaged. We’ve seen deaths directly attributed to marijuana legalization. We’ve seen marijuana slipping through Colorado’s borders. We’ve seen marijuana getting into the hands of kids.”

As difficult as it is to forecast the long-term social impact of marijuana, it may be even tougher to predict the national political repercussions of legalization -- though as a bellwether state, Colorado offers some clues.

The state's voters in 2012 overwhelmingly supported the legalization ballot initiative after marijuana activists spotlighted the scientific evidence that shows cannabis consumption involves far fewer health and social consequences than alcohol consumption. It was a shrewd political message in a state with ubiquitous microbreweries and a beer-themed baseball stadium.

When Colorado's Democratic Gov. John Hickenlooper opposed the marijuana measure, the ballot measure's proponents noted the irony of a former beer brewer who made his personal fortune promoting alcohol suddenly railing on the recreational use of another, less-toxic drug. They also noted that stalwart conservatives such as former Colorado congressman Tom Tancredo, a Republican , supported legalization.

Yet other prominent Colorado Republicans are renewing their public opposition. For example, Colorado U.S. Rep. Mike Coffman last week told a national radio program that "it's a horrible decision that Colorado made," and he previously argued to a local radio station that legalization will deter Fortune 500 CEOs from relocating their companies in the state.

In national Republican circles, the politics are just as fluid as they are in Colorado. Christie's support for the drug war had long been unquestioned orthodoxy, but there are signs that may be changing among the GOP's rank and file.

Polling-wise, a July HuffPost/YouGov survey found 61 percent of Americans support Colorado's new marijuana law. That includes a slim majority of self-described Republicans. In Colorado, a March 2014 Public Policy Polling survey found 57 percent of all voters supporting legalization. That includes 40 percent of GOP voters.

Those fast-shifting numbers could foreshadow a Republican presidential primary squabble over drug policy, especially if the primaries end up pitting Christie against the more libertarian-minded Paul. That may be why Christie has tried to couple his tough talk on marijuana with promises of at least some drug policy reform. He used his January inauguration speech to declare, "We will end the failed war on drugs that believes that incarceration is the cure of every ill caused by drug abuse."

He has since proposed a modest funding increase for special drug courts, which mandate treatment rather than incarceration for low-level drug offenses.

In an interview with IBTimes after Christie's visit to Denver, the Marijuana Policy Project's Mason Tvert said GOP candidates would lose votes in Colorado and across the country by campaigning against legalization.

"Republicans have little to gain by criticizing Colorado's decision to end marijuana prohibition," said Tvert, who was one of the masterminds of the 2012 ballot initiative. "A rapidly growing majority of Americans, including conservatives, think marijuana should be legal for adults. By and large, voters appear to have far more interest in other issues. A staunch Republican is not going to vote for a candidate they consider 'too liberal' on health care, taxes, or abortion just because that candidate is tough on marijuana. Republicans would be wise to embrace marijuana policy reform, which could send a message to unaffiliated voters that they are a little more forward-thinking and independent-minded."