Advocates of legislation to combat painkiller and heroin abuse are balking at changes House Republicans have made to a Senate-passed bill, arguing the revisions would compromise drug addiction prevention and recovery programs.

The House Judiciary Committee on Wednesday is scheduled to begin considering legislation to address the opioid crisis, a major priority for members in both chambers this election year.

But there have been simmering tensions between House Republicans and the senators who led the effort to get an opioid bill through the upper chamber over how quickly the House is moving and the specifics of the legislation being proposed.

“Some of the most important ideas are missing from the House Judiciary Committee’s alternative,” Sen. Rob Portman (R-Ohio), who co-authored the Senate’s opioid bill, said on Tuesday. The Senate passed the legislation last month 94-1, and Portman called it “comprehensive. No other bill comes close.”

Portman faces a tough reelection race this year, and he is heavily promoting the opioid bill as part of his campaign.

House leaders have dismissed the concerns, arguing that many of the worries expressed by Portman and advocacy groups are addressed either by expanded grant programs elsewhere in the legislation or under bills being examined by several committees.

“You’ll see streamlining a number of grants,” House Majority Leader Kevin McCarthy (R-Calif.) said on Tuesday, adding that the overall House bill would be “a real improvement” over the Senate’s legislation.

At issue are how grants for treatment, prevention and recovery programs should be distributed. The House bill seeks to reduce the number of grant programs while giving states and localities more freedom in how they use the federal funds. But advocates of the Senate approach said they are concerned this will deemphasize programs they think are important but are not specifically addressed under the House approach such as youth-focused education campaigns, recovery support centers and programs to collect unused painkillers.

Consolidating programs under one funding umbrella “risks imbalance, as many states and localities seeking funding may only prioritize one or two of these activities,” Harm Reduction Coalition Policy Director Daniel Raymond wrote in a letter to House Judiciary Committee leaders on Monday, one of several advocates to pen alarmed notes to lawmakers.

But House leaders insist their final product will be better than the Senate bill, noting that their bill also puts more money toward the crisis — the House bill authorizes $103 million for programs, compared with the $77 million in the Senate bill.

McCarthy said this week that he planned to put a package of bills on the floor the week of May 9, and that he is already discussing with Senate Majority Leader Mitch McConnell (R-Ky.) ways to quickly settle differences and send a final product to the president’s desk.

Part of the process, McCarthy stressed, is allowing individual committees to address the parts of opioid legislation that relate to their jurisdiction.

For now, advocates are focusing on initiatives absent from the House legislation that they argue would help improve recovery efforts, especially those that target young people.

“Prevention, treatment and enforcement cannot solve the opiate problem without recovery supports,” Patty McCarthy Metcalf, executive director of Faces & Voices of Recovery, another advocacy organization, said in a statement on Monday.

Mike DeBonis contributed to this story.