Democrats are trying to take back an issue Donald Trump effectively stole from them during the 2016 presidential campaign: the high cost of prescription drugs.

Trump repeatedly railed against pharmaceutical companies during the campaign and after taking office, promising that prices would drop and accusing drug companies of “getting away with murder.” But more than a year into his tenure, Trump has taken only limited action, and drug prices continue to climb.

While Trump this week is again slated to deliver a delayed speech on drug prices, Democrats are pushing proposals they hope will compare favorably to Trump’s and give them the upper hand on an issue polls consistently rank as among voters’ top concerns.

Democrats focused on drug prices in their “Better Deal” agenda for if they take control of Congress, including a proposal to let Medicare use its buying power to bargain down the cost of medications.

Drug price negotiation is a longtime plank of the Democratic platform, but Trump embraced the proposal during his 2016 campaign. He told an enthusiastic crowd in New Hampshire that it could unlock huge savings. “We don’t do it. Why? Because of the drug companies,” he said then.

So far, he hasn’t followed through. A year ago, Democratic Reps. Elijah E. Cummings (Md.) and Peter Welch (Vt.) said Trump had promised to back their push for price negotiation in a White House meeting. But when the two Democrats introduced legislation to authorize price negotiation in October, Trump didn’t offer an endorsement or feedback.

Democrats are also promising to appoint a “price gouging” enforcer who would fine drug companies if their price increases surpassed certain thresholds — another piece they believe will show voters that Democrats are prepared to tackle the issue in a way Trump hasn’t.

“There’s no question that it provides an opening for us,” said Rep. Richard E. Neal (Mass.), the top Democrat on the Ways and Means Committee.

“Well, I don’t know what he’s done. I mean, prices continue to go up,” said Sen. Debbie Stabenow (Mich.), one of 10 Democratic senators up for reelection in November in states Trump won. “I think the president should keep his promises.”

Trump had been scheduled to deliver his speech on prescription drug prices April 26, but it was delayed and is now expected in coming days. White House officials had signaled that Trump would use the speech to build on technical proposals the administration had already advanced, but Health and Human Services Secretary Alex Azar hinted recently that the president may surprise people.

“We’ll be building on the proposals in the president’s budget, but he wants to go further,” Azar said at the World Health Care Congress on Wednesday. “I believe we can help lower the cost of medicine while still promoting research that will transform the future of care. Doing both is the only way forward.”

It remains uncertain what proposals the president will lay out, and Trump has in the past made large-scale proposals with little warning — at times even contradicting his administration’s other efforts. But there’s been little evidence from his actions so far that he will go all in on a major new initiative.

Voters consistently cite health-care costs, including high prescription drug prices, as one of their top concerns, and lawmakers in both parties say it’s one of the issues raised most frequently by their constituents back home. A Kaiser Health Tracking Poll in March found that 52 percent of Americans said passing legislation to lower prescription drug prices should be a “top priority” for Trump and Congress. Nearly three-quarters of Americans said pharmaceutical companies have too much influence in Washington, a view shared by both Democrats and Republicans.

In risky timing for the GOP, voters are likely to see their health insurance premiums jump again when new rates are rolled out this fall, just ahead of the midterm elections. And after years when the GOP blamed President Barack Obama and the Affordable Care Act for all the problems consumers encountered in health care, Republicans who now control the White House and both chambers of Congress may no longer be able to deflect the blame.

“Simply put, there is no issue where there is greater vulnerability for Republicans or greater opportunity for Democrats than the issue of health care,” said Geoff Garin, a longtime Democratic pollster who’s been conducting focus groups on the issue.

Some Republicans acknowledge political concerns that their party will take the blame for rising costs that Trump and the GOP Congress have failed to tame.

“Absolutely. . . . It does concern me,” said Rep. Phil Roe (R-Tenn.), a practicing obstetrician. “What concerns me the most are my patients at home. Not the political price, but the actual price that folks have to pay, or they don’t get the care if it’s too expensive.”

Prices for the 20 most-prescribed brand-name drugs increased an average of 11 percent each year for the past five years, according to a Wells Fargo research note that looked at the medications that were prescribed most often in 2017. Prices have continued to rise this year, Wells Fargo said.

The true cost of drugs is difficult to measure, as different patients and insurers pay a wide range of prices. Still, actuaries at the Centers for Medicare and Medicaid Services projected in February that spending on prescription drugs would grow at 6.3 percent per year over the next decade, faster than spending on any other health-care service.

And for those whose insurance plans have high deductibles, that means expensive out-of-pocket payments that climb year after year.

The issue is far easier to campaign on than to solve, because of both the power of the drug lobby and the complexity of the byzantine system, which Democrats themselves failed to get a grip on during passage of the Affordable Care Act.

Health policy experts who have been analyzing the proposals advanced by the Trump administration so far argued that the measures would leave the high prices of drugs basically untouched while providing needed relief for some seniors’ out-of-pocket costs.

An analysis of some of the proposals in the president’s budget by a team at the Johns Hopkins Drug Access and Affordability Initiative found that there could be short-term benefits for some Medicare beneficiaries.

The analysis found that the proposal with the biggest impact for individuals would be passing rebates negotiated on drugs directly to Medicare beneficiaries at the pharmacy counter. Half of enrollees in stand-alone prescription drug plans would benefit from this change, saving on average $264. But most of those savings would be concentrated among the small fraction of people taking high-priced specialty drugs.

“They’re doing some modest, really marginal things that would be positive,” said Steven Knievel, an advocate at Public Citizen, a health watchdog group. “ ‘Small potatoes’ is too generous a term.”

Indeed, industry insiders have gained confidence under the Trump presidency, as early rhetoric blaming drugmakers for prices has transformed into a tangled debate over the role of middleman industries — such as insurers and pharmacy benefit managers — in drug prices.

As they seize on the issue anew, Democrats have begun linking high drug prices to the new GOP tax law, accusing drug companies of reaping a windfall from the legislation but failing to pass those savings down to consumers. At a recent Senate Finance Committee hearing, Sen. Claire McCaskill (Mo.), one of the most endangered Democrats in November, railed against drug companies and proclaimed that the industry has a “vise grip” on the Republican Congress.

Sen. Tammy Baldwin (D-Wis.), who also faces a reelection race in November in a state won by Trump, devoted an early television ad to the issue, showcasing her partnership with Sen. John McCain (R-Ariz.) on a bill requiring drug companies to notify the federal government before raising the prices of certain drugs higher than 10 percent.

Republicans are just as willing as Democrats to acknowledge voters’ concerns about prescription drug prices and health-care costs in general, but many continue to argue that Trump will deliver on the issue.

Rep. James Comer (R-Ky.) said prescription drug costs are the top health-care issue raised by voters in his rural district. He said he hopes to see Trump address the issue of the availability of generic drugs, adding that he’s even open to allowing reimportation of cheaper drugs from Canada for American consumers.

And if the president doesn’t deliver?

“The voters of my district are pretty solidly behind the president. I think Congress will get more of the blame than the president. That’s usually the way it works. He’s pretty good at that,” Comer said. “But I want to work with president. I think he’s committed to trying to do something to improve health care in America.”