WASHINGTON — White House officials revealed Tuesday they will seek nearly $1.2 billion in new federal funding over the next two years to address the growing problem of heroin and prescription opioid use, an epidemic that has become an increasingly important policy priority among the nation’s politicians.

The centerpiece of the proposal is $1 billion in mandatory funding over two years to expand access to treatment for prescription drug abuse and heroin use, $920 million of which would go to the states. Another $500 million, some of which is a continuation of existing funds, would support work by the departments of Health and Human Services and Justice to expand not just treatment but access to the overdose-reversal drug naloxone and to support targeted enforcement activities.

Officials from both parties have intensified their focus on opioid use as it has taken an increasingly heavy toll on both rural and urban communities. Last month, Obama appointed Agriculture Secretary Tom Vilsack to lead a new interagency effort focused on addressing the issue in rural America, while Senate majority leader Mitch McConnell, Republican of Kentucky, and Senate minority leader Harry Reid, Democrat of Nevada, have agreed to take up legislation on the issue. The total number of US deaths linked to opioids — a class of drugs that includes prescription pain medications as well as heroin — reached 28,648 deaths in 2014, exceeding the number stemming from car crashes.

Speaking to reporters Tuesday, Health and Human Services Secretary Sylvia Matthews Burwell said the funding includes $460 million over two years for what she called ‘‘evidence-based intervention efforts,’’ adding that while it would have to be spread out, ‘‘we want to try to move that money as quickly as possible’’ to the states.