ORLANDO, Fla. — President Donald Trump accused Democrats of trying to "destroy our country" as he officially kicked off his re-election campaign with a packed-house rally at the Amway Center here Tuesday night.

"Our radical Democrat opponents are driven by hatred, prejudice and rage," he said, pointing to House efforts to investigate his 2016 campaign's ties to Russia and possible obstruction of justice by the president. "They want to destroy you and they want to destroy our country as we know it. Not acceptable, it’s not going to happen. Not going to happen."

The federal Russia probes aren't just an attack on him, he told the crowd — "they are really going after you. ... They tried to erase your vote, erase your legacy of the greatest campaign and the greatest election probably in the history of our country."

But in the political version of a revival meeting, Trump stuck mostly to familiar rounds of call and response.

One after another, he delivered familiar applause lines designed to induce chants — "build the wall," "CNN sucks" and "lock her up" among them — that have been mainstays of his campaign rallies for four years now.

The tenor of Trump's remarks wasn't a huge surprise to observers. His strategy for re-election, say allies, isn't based on persuading a significant share of the majority of Americans who disapprove of his job performance to vote for him. Rather, he's trying to super-charge his fans with enough energy that they show up in force for him and spread the word to their friends and neighbors.

Instead, given both his inability to improve his approval ratings and Democrats' failure to diminish them, Trump's remarks appeared designed to appeal to the subset of potential voters already attracted to the messages he's been driving all along.

That goal was evident in his decision to aim a message directly at his base during an appearance in Orlando, which sits at the heart of Florida's I-4 corridor. The region is a traditional swing area in a swing state that is crucial to Trump's fate, and his answer to that challenge was pumping up his existing supporters rather than reaching out across the political divide.

Rep. Stephanie Murphy, D-Fla., a leader of the moderate Blue Dog Democrats who represents a neighboring district, said Trump came to the right place, and that her party will have to find the right mix of swing voter outreach and base Democratic enthusiasm to defeat him.

"President Trump is strategic to target central Florida in his re-election campaign," Murphy told NBC News. "In order for Democrats to win statewide, we need to recognize the complexities of our Democratic base, while also developing a strategic, well-funded and well-organized effort to persuade voters, especially independent voters in central Florida."

Her concern, she said, is that members of her own party are playing into Trump's characterizations of Democrats as too hidebound and too far to the left.

"America will never be a socialist country," Trump said Tuesday night. "Republicans do not believe in socialism. We believe in freedom, and so do you."

Murphy, who has been vocal in her criticism of the handful of her colleagues who embrace "democratic socialism," said her party is in peril of helping Trump win a second term.

"National Democrats need to realize that what may be good politics in the Bronx or California can backfire in states like Florida," she said. "Simply put, if we want to beat Donald Trump, we must put winning over political purity."

While Trump played all the classic refrains for the faithful, he did hit a few new or rarely used notes in a speech that ran for more than 80 minutes, including a brief appearance by departing White House press secretary Sarah Sanders.

The biggest wrinkle was the voice vote Trump held on whether to maintain his old slogan "Make America Great Again" or change it to "Keep America Great." The video boards on the sides of the arena featuring the latter strongly hinted at which choice his supporters were expected to pick.

"Keep America Great" won by a vocal landslide.

And then Trump told the crowd what it had come to hear.

"With every ounce of heart and might and sweat and soul, we’re going to keep making America great again and then we will indeed keep America great," he said. "We will keep it so great, better than ever before. We’re going to keep it better than ever before. And that is why tonight I stand before you to officially launch my campaign for a second time as president of the United States."