(CNN) Republican Arkansas Sen. Tom Cotton spoke out against bipartisan efforts to reform America's criminal justice system at a conservative think tank in Washington on Thursday, saying, "If anything, we have an under-incarceration problem."

"For the vast majority of crimes, a perpetrator is never identified or arrested, let alone prosecuted, convicted and jailed," Cotton said at the Hudson Institute

The Arkansas senator has been a staunch opponent of bipartisan legislation which would push to reduce mandatory minimum sentences for nonviolent criminal offenders. The bill would also give judges greater discretion on sentencing for low level drug related crimes.

Cotton called efforts to restore voting rights to felons, and making it easier for ex-felons to seek employment "dangerous."

"Law enforcement is able to arrest or identify a likely perpetrator for only 19% of property crimes and 47% of violent crimes. If anything, we have an under-incarceration problem," Cotton said.

"The truth is you cannot decrease the severity and certainty of sentences without increasing crime," Cotton said. "It's simply impossible."

Criminal justice reform advocates claim the severity of the sentencing does not have much of an effect on repeat offenders and crime rates.

"When he says we have all of these unsolved crimes, so that's why we should be filling the prisons even more, where is he going to get the resources to prosecute those if we're spending so much money putting a nonviolent drug offender in prison for 30 years," said Kevin Ring, Vice President of Families Against Mandatory Minimums, a non-profit organization.

"This is a misallocation of resources. No one is trying to make a trade off between safety and security. We're saying we can get more safety if we use our resources efficiently."

While Cotton has conservative allies on the issue, such as Sen. Jeff Sessions, and former presidential candidate Sen. Ted Cruz, he also has opponents from his own party, most notably Senate Judiciary Chairman Chuck Grassley.

The Iowa senator, who has reached a hand out to Senate Democrats on the issue, shot back at the Arkansas senator's criticism.

"The opponents of the Sentencing Reform and Corrections Act will stop at nothing to derail an historic bill aimed at safely and sensibly reducing excessive sentences while preserving important law enforcement tools to take down large criminal organizations," Grassley said in a statement to CNN. "It's supported by coalitions representing more than 400 organizations, including important law enforcement groups like the Major County Sheriffs Association and the International Association of Chiefs of Police, which undercuts the opposition's arguments. We continue to make progress with the bill and remain hopeful that it will be considered by the full Senate."