Former President Donald J. Trump, who has been itching for months to focus on a likely matchup between him and President Biden in November, previewed on Saturday a likely general-election message, extensively attacking Mr. Biden at an event in Nevada, a critical battleground state.
Further proof of Nevada’s importance could be seen a mile away, where Vice President Kamala Harris cast the fight against Mr. Trump, should he wrap up the nomination, as a battle for democracy.
Though Mr. Trump was ostensibly visiting Las Vegas to encourage his supporters to turn out for the Nevada caucuses on Feb. 8, he devoted much of his speech to Mr. Biden’s handling of the surge of crossings at the southern border, which he called “a weapon of mass destruction” internally destroying the United States.
And Mr. Trump, who currently faces four criminal cases that he casts — without evidence — as attempts by Mr. Biden to wrest the election from him, wielded the language of the justice system to suit his purposes.
“What Joe Biden doing is a crime against our nation,” Mr. Trump said. He later added: “With your vote, he will be judged and convicted by the American people for this atrocity that he’s done.”
Saturday’s speech was in many ways a return to form after a month in which Mr. Trump had escalated his attacks against his rivals in the Republican presidential primary as he scored decisive wins in Iowa and New Hampshire.
Mr. Trump now seems to be marching toward the general election, but he is not yet the party’s nominee, and his lone remaining rival for the nomination, Nikki Haley, is doing everything she can to remind him that she remains in the race.
Mr. Trump’s supporters on Saturday said they had largely moved past the Republican contest, though Ms. Haley is still running. “It’s like the Kenny Rogers song — you need to know when to fold ’em,” Joe Sandoval, 74, said. “I don’t think she’s even a concern for him at this point.”
Mr. Trump and his team are preparing to fight Ms. Haley in her home state of South Carolina, the site of their next electoral battle, on Feb. 24. The former president took glancing swipes at her on Saturday, mostly accusing her of betraying Republican ideals and her conservative roots.
“Nikki Haley made a corrupt deal to sell out to the radical left, taking the Democrat money from donors,” Mr. Trump said.
But Mr. Trump’s victory in Nevada’s caucuses is a foregone conclusion. Ms. Haley is on the ballot for a presidential primary on Feb. 6 that will not count toward the G.O.P. nomination, so she is skipping the state entirely. The caucuses — which will determine who gets the state’s delegate prize — feature Mr. Trump without a single major competitor.
“Nevada will certainly be a good messaging opportunity for Trump, because he’s going to win all the delegates here, and he will win unopposed,” said Jeremy Gelman, an associate professor of political science at the University of Nevada, Reno. “He will be able to say he swept Nevada.”
Still, those attending Mr. Trump’s speech in Las Vegas, held at Big League Dreams, a sports park, admitted to some confusion over the dueling contests, an issue Mr. Trump addressed.
“Don’t worry about the primary, just do the caucus,” Mr. Trump told his supporters.
Later, he delivered a more mixed message. “Don’t waste your time on primary,” he said. “Waste all of your time on caucus.”
His phrasing, inadvertent or not, reflects the view of the primary that Mr. Trump, long the front-runner, has had for months: that it is a distraction delaying him from taking on Mr. Biden.
On Saturday, Mr. Trump attacked a Biden-backed bipartisan immigration deal, saying it was “not designed to stop illegal immigration.” Mr. Trump has been pressing Republican senators to oppose a deal, and he told them in his speech to “blame me” if it failed.
He also signaled his intent to court Hispanic voters, a key constituency in Nevada, and an important part of the Democratic coalition. Polls have shown Mr. Trump gaining their support.
Mr. Trump charged that Mr. Biden had “devastated the Latino community” economically, and said Hispanics had been “better off” financially under his administration.
He also suggested that Black and Latino voters were the “single most affected people by what’s happening at our border,” but provided no specifics.
In a statement, a spokesman for Mr. Biden’s re-election campaign, Ammar Moussa, said, “Donald Trump demonstrated tonight he’s campaigning against solutions for the American people, and is actively rooting against America,” adding that Mr. Biden was “the only candidate focused on governing and addressing the issues the American people demand action on.”
Both parties are looking to November: Outside Mr. Trump’s event, the Democratic National Committee flew a plane overhead with a banner reading “Donald Trump: Ban Abortion, Punish Women.” The party is expected to make abortion a central issue in November.
A mile away, Vice President Harris’s event felt like an alternative universe, with some voters wearing masks and voicing support for gun control while an Olivia Rodrigo song played and a local dance team performed.
Ms. Harris riled up the crowd with a list of the administration’s accomplishments and suggested that they contrasted with Mr. Trump’s priorities.
“In his comments today, as always, he made clear his fight is not for the people. His fight is for himself,” she said, as hundreds booed.
“Freedom is on the ballot, and our democracy is on the ballot,” Ms. Harris said. “This is about standing for the kind of country we want to live in.”
Sara Diss, 74, said she would be voting to re-elect Mr. Biden and Ms. Harris. “I want somebody that is going to protect democracy,” she said. “Trump, he’s out to get revenge.”
Still, even at an event aimed at generating excitement among the Democratic faithful, some voters acknowledged harboring doubts.
Daphne Silva, 25, said she had always voted for Democrats, including for Mr. Biden in 2020, and planned to vote for him again in November.
But, she added, “I’m a little bit hesitant based on the stuff he’s doing around the war.” She said she wished that he would be more critical of sending aid to Israel and that Democrats had fielded a larger roster of candidates for voters to choose from.
“I wish there were more options,” Ms. Silva said, “but I think it’s too late.”