Trump has lost his senior advantage. And that could cost him in November.

WASHINGTON — Jay Copan was part of the coalition that made Donald Trump president in 2016. Now he’s had enough and plans to send Trump into retirement.

Copan, 68, who lives in Raleigh, North Carolina, considers himself fiscally and socially conservative. A white man who is a registered independent in a swing state, he has voted Republican in each of the last nine presidential elections. He supports Trump’s tax cuts, energy policy and judges. He’s precisely the type of voter Republicans should be able to win — and can’t afford to lose.

But Copan says he’ll vote for Joe Biden this fall.

“At the end of the day, I want this to be a better country for my grandkids growing up. And having a president who’s a pathological liar, a sociopath, a narcissist, a misogynist and a bully is not the way I want to leave this country,” Copan said. “In spite of my views on the issues, I don’t see any way I could support him to be president for another four years because of how he’s behaved.”

June 29, 202005:56

Copan represents a group of voters whom Trump, who is 74, should worry about: Americans over 65 who are defecting to Biden. Seniors have voted for the Republican candidate in every presidential election since 2004, according to exit polls. They favored Trump by 8 points in 2016, according to NBC News exit polls.

But most surveys this month show Trump trailing Biden among this group, down by 2 points in a New York Times/Siena College poll, 4 points in a CNN poll, 8 points in an NBC/Wall Street Journal poll and 8 points in a Quinnipiac University poll.

Trump’s sliding support among the key demographic has contributed to his trailing Biden by 9.4 points in the FiveThirtyEight average of surveys as of Monday.

With voters under 45 increasingly preferring Democrats, losing senior citizens could choke off Trump’s path to re-election. Some allies worry that he’s antagonizing elderly voters with his mockery of 77-year-old Biden’s placid temperament and verbal stumbles with the nickname “sleepy Joe” and his persistent insinuations that Biden is losing his mental faculties.

“The hot air slipping out of President Trump’s campaign balloon among seniors is certainly a cause for concern,” Dan Eberhart, a Republican donor and Trump supporter, said in an email. “His angry rhetoric and constant poking at Biden’s age and ailments could be a sizable part of the problem here. This is a group of people used to being catered to and respected.”

Download the NBC News app for breaking news and politics

The shifting views of senior citizens were on display when a pro-Trump parade was protested in The Villages, a GOP-leaning retirement community northwest of Orlando, Florida. A video of the clashes went viral after the president tweeted (and then deleted) a clip that included a supporter with Trump gear who was shouting “white power” at someone who had called him racist. (Trump’s spokesman later said he didn’t see that part.)

Trump campaign spokeswoman Courtney Parella said that “as long as President Trump is in the White House, America’s seniors can rely on him to act in their best interest as he delivers the Great American Comeback.”

“America’s seniors are the backbone of this nation, and President Trump is dedicated to protecting their livelihoods,” Parella said in a statement. “While Joe Biden serves as a puppet of the far left, bending to radical ideas that threaten our economy and our health care system, President Trump is looking out for our seniors on Medicare.”

Peter Hart, a Democratic pollster who helps conduct the NBC/Wall Street Journal poll, said Biden’s advantage among older voters shows that “there’s an awful lot of wind at his back.”

Speaking of Trump, he said, “Those things that most frighten seniors, health care being among them — he can talk to them stylistically, but he can’t talk to them substantively.”

But Hart cautioned that there’s plenty of time before Election Day and that seniors’ attitudes can change: “I like to warn people: Don’t over-emphasize the June surveys. Because it can be misleading.”

Two weeks ago, the president held a White House roundtable called Fighting for America’s Seniors in which he proclaimed his “unwavering devotion to our senior citizens.”

He touted his administration’s work launching the National Elder Fraud Hotline and charging scores of defendants accused of defrauding seniors, his efforts to cap the cost of insulin and his promise to keep “defending Medicare and Social Security.”

But Trump’s other actions and rhetoric may be hurting him with older voters.

He has encouraged states to reopen their economies amid the coronavirus pandemic, which is disproportionately fatal among elderly people. He recently suggested without any evidence that a 75-year-old Buffalo man who was pushed by police and injured was a plant by the far-left “antifa” movement. He has launched blistering attacks on universal voting by mail, an option many senior citizens prefer.

Biden campaign spokesman TJ Ducklo said the former vice president’s plans for reopening the economy include measures to protect seniors from COVID-19, and he said Biden plans to preserve the Affordable Care Act, which Trump is fighting in court to overturn.

Trump won older voters in 2016 by promising economic prosperity and hitting nostalgic notes of an era before free trade and globalization took a toll on America’s once-vibrant manufacturing sector. He benefited from the high unpopularity of his opponent at the time, Hillary Clinton, winning decisive votes from Americans who were skeptical of both candidates.

One of them was Copan.

“I absolutely could not vote for Hillary — had enough of the Clintons,” he said. “I literally held my nose and voted for Trump. I thought it was the lesser of two evils. I just didn’t realize how evil he could be.”