In their private strategy sessions leading up to last month’s debate, President Biden and his advisers homed in on what they saw as one of their most effective political messages against Donald Trump - the administration’s success capping drug prices for millions of seniors, according to two people who spoke on the condition of anonymity to describe the preparations.

But during the June 27 debate, Biden spent an excruciating 10 seconds searching for the words to explain what his administration had done to lower seniors’ prescription drug costs, before abruptly telling the 51 million viewers: “We finally beat Medicare.” (The president appeared to be trying to say that he had finally defeated the drug companies that had long resisted letting the government negotiate the prices that Medicare paid.)

The gaffe represented just one example of a pattern that is fueling the effort to push Biden aside as the Democratic Party’s nominee. Congressional Democrats and the administration believe Biden has major accomplishments to tout and ambitious policy ideas for the next four years. And yet Biden’s intensifying struggles in recent weeks to describe those policies - on abortion, housing, child benefits and more - have cast doubt over his effectiveness as the party’s leading messenger, even beyond the Democratic angst about the debate.

“It’s pretty obvious why Democrats are intensely frustrated: They believe they have strong affirmative arguments to make, both in defense of what the administration has done but also what they propose to do - but it’s being totally overshadowed by Biden’s inability to articulate those arguments,” said Bill Galston, who served as a senior aide during Bill Clinton’s administration.

Biden’s decades of verbal stumbles are well-documented, and his defenders have blamed some miscues on his lifelong battle with a stutter. Also, his syntax problems come and go. On foreign policy, for instance, the president’s allies say he has a good grasp of the issues. During a July 11 news conference at the conclusion of the NATO summit, Biden gave an accurate overview of the arcane rules of inbound investment into China and domestic concerns about Chinese overproduction in green manufacturing.

“Since the debate, thousands of Americans have cheered the President in Michigan, North Carolina, Nevada and across the battlegrounds - not only because his words moved them, but also because his policies touch their lives everyday: whether it’s capping insulin at $35 month for seniors, repairing their bridges and roads, creating millions of union jobs or eliminating exorbitant junk fees,” campaign spokeswoman Lauren Hitt said in a statement. “Joe Biden grew up in Scranton and understands personally what Americans are facing at their kitchen table - and that’s why he has been so effective at delivering results that actually matter to people.”

Trump has had his own communication struggles, underscored by a rambling, 92-minute acceptance speech at the Republican National Convention this week, the longest such address in history. The former president skipped over details of his policies and repeatedly went on tangents - giving Democrats hope that they just need to provide a more compelling alternative to win in November.

Still, Biden’s repeated struggles to describe his own accomplishments and his goals for a second term have taken on new urgency in a campaign in which he lags behind Trump, according to most public polls. Those struggles have led the White House to carefully manage the president’s public appearances, limiting Democrats’ messaging even as Biden tries to shift discussion away from his age and toward the two parties’ approaches to government. And his stumbles are compounding the frustrations of Democrats who believe they would have a clear advantage over Republicans in a race about policy contrasts - especially if they can put a candidate onstage who can build a case for Democrats’ plans while deconstructing Trump’s.

“I believe President Biden must do more to demonstrate he can campaign strong enough to beat Donald Trump,” Sen. Patty Murray (D-Wash.), who chairs the Senate Appropriations Committee, said in a statement this month. “Our nominee must be able to articulate what Democrats have accomplished and everything we will do to make life better for American families and protect their freedoms - like making child care affordable and accessible for parents everywhere and restoring abortion rights for women in all 50 states.”

Conservatives say replacing Biden with a new candidate to espouse similar policy proposals may not prove sufficient to guarantee Democrats’ success in November, particularly if that replacement could be tied to his record. Harris has been the vice president throughout Biden’s tenure, including the surge in inflation.

“The vast majority of voters, especially those who decide elections, are not that ideological ... They’re upset about inflation, and cost of living, and that’s what polls continually show people are concerned about,” said Avik Roy, founder of the Foundation for Research on Equal Opportunity, which advocates free markets, and a former adviser to leading GOP policymakers. “It’s not enough to just be articulate in expressing the message -- if your governing background contradicts your message, that’s a problem, too.”

Biden has tried to ramp up his campaign after his poor debate performance, but those appearances have brought new headaches. (Since Wednesday, he has been self-isolating in Rehoboth Beach, Del., after testing positive for the coronavirus.)

In a speech to the NAACP on Tuesday in Las Vegas, the president previewed a White House policy proposal to strip tax benefits from certain landlords who raise annual rent by more than 5 percent. Democrats view the idea as a populist proposal to win over young voters stressed by high housing costs and a contrast to Trump, a billionaire real estate developer. But Biden mischaracterized the plan.

“Look, folks, the idea - the idea that corporate-owned housing is able to raise your rent three, four hundred bucks a month or something - under what I’m about to announce, they can’t raise it more than $55,” Biden said. (Biden’s plan would need congressional approval.)

Biden also appeared to run into trouble discussing his plans for drug-price cuts.

“It will save taxpayers, just what I did on the first round on deal- - dealing with Medicare. It saves the taxpayer $160 billion - because they don’t have to pay these exorbitant prices to these - anyway, I won’t,” he trailed off in his NAACP speech.

Biden’s struggles to explain his efforts to protect abortion access - an issue central to Democrats’ 2024 electoral hopes - also have frustrated allies and supporters. The president, a Catholic who once opposed abortion and often avoids saying the word “abortion” when asked about it, offered a convoluted response when pressed during the debate on legal limits on abortion.

“First time is between a woman and a doctor. Second time is between the doctor and an extreme situation. And a third time is between the doctor - I mean, it’d be between the woman and the state,” Biden said.

Biden inexplicably veered into talking about immigration in another abortion answer: “Look, there’s so many young women who have been - including a young woman who just was murdered and he went to the funeral. The idea that she was murdered by - by - by an immigrant coming in and [inaudible] talk about that,” the president said, according to the transcript.

Reproductive rights activists characterized the comments as a major missed opportunity to draw a contrast with Trump, who appointed three of the five Supreme Court justices who voted to overturn Roe v. Wade.

Taxes are another area where Democrats believe they should have an edge over Trump, who in 2017 signed into law a tax plan that disproportionately benefited the rich.

But in an interview with Univision that aired Thursday, Biden veered from a discussion of his pledges to raise taxes on billionaires into comments about the nation’s education system.

“Look what’s happening in our schools,” he said, according to a Univision transcript. “What’s happening in schools, all the stuff about gay and lesbian children. Look how they’re being. Anyway. And so many things we could do.”

The president then alluded to his expansion of the child tax credit, which lifted millions of families out of poverty and expired at the end of 2021: “Everybody who had a child under, making under $200,000, or if they’re making $200,000, they got, they got a 38 - they got a write-off on their taxes.”

Biden’s actions on prescription drugs present a particularly challenging test: His accomplishments can be difficult to explain simply, such as the provision that requires pharmaceutical companies to negotiate the prices of their drugs with Medicare, a long-sought goal for policymakers. But the issues poll well when voters understand them, so Democrats are eager to bring them up.

Biden’s drug-pricing wins are “the number one testing proof point that I’ve seen in focus groups that I personally observed,” said a communications strategist at a major Democratic-aligned group, speaking on the condition of anonymity to be candid. “Lots of people said they would rein in Big Pharma; he actually got it done.”

But many Americans are unaware of Biden’s efforts, which include capping seniors’ out-of-pocket spending on drug costs at $2,000 per year. About one-quarter of voters said they knew that a federal law would limit out-of-pocket spending on prescriptions for Medicare beneficiaries, according to a poll released in May by KFF, a nonpartisan health-care think tank. Thirty-six percent of voters said they knew that a law required the federal government to negotiate the price of some prescription drugs for Medicare.

Leslie Dach, founder of Democrat-aligned advocacy group Protect Our Care, said he was frustrated by Republicans trying to co-opt the drug-pricing issue. He pointed to a video introducing Sen. J.D. Vance (R-Ohio) as Trump’s running mate on Wednesday night that suggested that the GOP would help rein in seniors’ drug costs. The claim incensed Dach, because Biden’s drug-price legislation did not receive a single vote from Republicans in Congress.

“We have winning issues. But we’re fighting against people who are extending the ‘big lie’ to every part of their campaign,” Dach said. “It’s a communications war.”

It’s not clear that Biden is well-equipped to fight it, even with the benefit of a teleprompter.

At a speech in Detroit last week, the president again tripped over his explanations about the drug price cuts. “By the way, I got criticized for taking on Medicare - I mean, on - taking on the drug companies and pharma for that. Well - well it’s -,” Biden said, according to the official White House transcript.

Toluse Olorunnipa contributed to this report.