Attorney General Eric Holder’s decision to lighten prison sentences for low-level drug dealers was a rare reversal in the government’s decades-long war on drugs and riled congressional Republicans who accused the Obama administration of again overstepping its executive-branch authority.

But many conservatives upset with the White House’s unilateral rewriting of the law also were quick to express interest in changing a federal initiative that cost more than $1 trillion and imprisoned tens of thousands of Americans since President Richard Nixon first declared a war on drugs in 1971.

Republicans backed a slew of Draconian penalties for drug crimes in the 1980s after drug-fueled violence sent the nation’s murder rates soaring and have since then feared that softening any of those penalties would make them look weak on crime. But conservatives are reevaluating the financial and social costs of a drug war, shifting the focus from punishing criminals to saving billions of dollars spent annually to battle drug violence.

“The largest portion of the Justice Department budget is the Bureau of Prisons,” said House Judiciary Committee Chairman Bob Goodlatte, R-Va. “And for every dollar that is spent incarcerating someone who may be able to receive a different form of punishment, that’s money taken away from fighting crime and terrorism.”

Even before Holder called for an end to mandatory minimum sentences for minor drug crimes, congressional Republicans — including party leaders like Sens. Rand Paul, of Kentucky, and Mike Lee, of Utah — were weighing whether sentences for non-violent offenders were too harsh.

The Republican-run House Judiciary Committee in May appointed a task force to study whether the federal code "over-criminalizes" certain offenses, including drug crimes. Two task force members — Rep. Bobby Scott, D-Va., and Rep. Jim Sensenbrenner, R-Wis. — will soon propose their first drug law changes.

Democrats, who in the 1990s advocated alternative responses, like midnight basketball leagues, to the drug problem, say Republicans have come to their way of thinking as drug use spread from cities to the suburbs and rural areas and started to have more of an impact within their own districts.

“It’s the results that shows this has not been effective,” said Rep. Sheila Jackson Lee, D-Texas. “Their constituents have been caught up in mandatory minimums in large numbers, too, young constituents that may have been caught up selling amphetamines and meth that has been growing in the Midwest and northwest. This is rounding up all of America.”

But Republicans worry that Holder’s foray into the debate last month will politicize an issue that was gaining bipartisan steam. Instead of telling his U.S. attorneys not to go after small-time dealers, Holder instructed them in some cases to hide from judges the amount of drugs intended for distribution to avoid triggering a minimum punishment.

“The way the attorney general is going about doing this does not build confidence in the fairness of sentences,” Goodlatte said.

Many congressional Republicans remain wary of abolishing mandatory minimum sentences and leaving criminal penalties entirely in the hands of judges.

Rep. Trey Gowdy, R-S.C., a former federal prosecutor, agrees that mandatory minimums don’t deter non-violent drug crimes. But without some guidance, a federal judge in Washington state could give a convicted dealer probation while a similar offender in Arkansas gets 20 years.

And there’s the reaction from voters in the district.

“If anything, people I talk to are likely to say they know more people who should be locked up than people who should be let out,” Gowdy said.

Goodlatte and Sensenbrenner expect Congress to take up the issue mandatory minimum prison sentences within the year as part of their discussions over comprehensive corrections reform. But the Republican lawmakers worry that partisan politics may still derail efforts to rewrite sentencing laws.

“My intent is to keep this strictly bipartisan, which means there will have to be give and take,” Sensenbrenner said. “I want to get it passed by the end of this Congress. This thing is very desperately needed.”