WINTERVILLE, N.C. — In the final days of the 2016 presidential race, Hillary Clinton's campaign has a consistent theme: Donald Trump.

There was a point at which Clinton's advisers had envisioned a more positive ending, but in the final days of a tight race, the Democratic nominee has backed away from emphasizing a sunny message of inclusiveness. Instead, she has dwelled repeatedly on a vision of a dark future of America under her opponent.

On Monday, the Democrats launched their version of Lyndon Johnson's “Daisy” ad from the 1964 campaign, an apocalyptic warning about the dire consequences of turning over America's nuclear arsenal to an untested and short-tempered leader — in this case Trump instead of Barry Goldwater.

Tuesday brought the campaign's first television ad featuring Trump's graphic boast, caught on an “Access Hollywood” video, about how he would grope women he found attractive and get away with it because of his fame.

And Thursday, at a rally here, Clinton was introduced by Mae Wiggins, whose application years ago to rent an apartment at a development owned by the Trump family was rejected — an incident that became part of a racial discrimination case against Trump and his father.

Trump, said Clinton, has spent his entire campaign offering “a dog whistle to his most hateful supporters.” She cited the endorsement of Trump earlier this week by the official newsletter of the Ku Klux Klan as proof those signals were being heard “loudly and clearly.”

“They said it's about preserving white identity, and they placed their faith and hope in him,” she said, noting the endorsement was written under Trump's slogan, “Make America great again.”

“You have to ask,” she added, “do any of us have a place in Trump's America?”

Clinton enlisted President Barack Obama's help urging those voters to the polls and lighting a fire under other Democrats, particularly young people. Speaking to students at Florida International University in Miami, Obama told voters now was the time to get serious about the choice.

“This isn't a joke. This isn't ‘Survivor.' This isn't ‘The Bachelorette.' ' he said, taunting the former reality TV star. “This counts.”

Trump, for his part, has displayed a concerted effort in recent days to remain disciplined, stick to his stump speech and not veer into the sort of perilous improvisations that often have sidetracked his campaign message.

Speaking in a cavernous equestrian center in Jacksonville, Fla., he stayed with a script that combined promises of a muscular economic resurgence with an exaggerated recitation of controversies that have dogged Clinton.

He alleged the FBI was “investigating how Hillary Clinton put the office of secretary of State up for sale in a violation of federal law” — an assertion that goes well beyond anything the bureau is known to be doing.

And in an effort to appeal to voters' memories of scandals during President Bill Clinton's tenure, he lamented “here we go again with Clinton — with the impeachment and the problems. She's likely to be under investigation for many, many years.”

Clinton has repeatedly called on supporters to imagine what America would look like under a President Trump.

“I would frankly rather be here talking about nearly anything else,” she said at a rally earlier this week.

“But I can't just talk about all the good things we want to do, because people are making up their minds,” Clinton said. “This is a consequential choice, so we've got to talk about something that frankly is painful.”

The steely, if reluctant, focus on her rival's flaws rather than her strengths reflects difficult truths that have vexed Clinton throughout the race.

She has had limited success in changing negative voter perceptions of her, an effort that was complicated again last week by the FBI's eleventh-hour renewed scrutiny of her emails as secretary of state.

That difficulty, combined with Trump's unchallenged ability to dominate public attention, has caused Clinton to accept as inevitable that her best path to victory involves keeping voters focused on her rival.

Clinton aides deny that her focus on the negative is in reaction to the FBI's renewed scrutiny of her emails.

And they insist that Clinton will return to making a more affirmative case for her candidacy as Election Day grows closer.

On Thursday they announced that the campaign's closing rally Monday night would feature not only Clinton, her husband and daughter, but Obama and the first lady.

At that rally, in Philadelphia, where she accepted the Democratic nomination in July, Clinton will outline how she intends to keep promoting the “American ideals of progress, inclusion, equality and strength that our founders enshrined in our Constitution,” the campaign said.

Noah Bierman reported from Washington, D.C. Los Angeles Times' Melanie Mason in Jacksonville, Fla., and Associated Press contributed.

Michael.memoli@latimes.com