"The big theme of the first month of their campaign was that they were the joyful campaign," Trump's running mate Sen. JD Vance said of Harris' campaign as he stumped in battleground Nevada. "And my friends, the joy is gone. The joy is gone from the Kamala Harris campaign."

During his remarks in the Treasure Island Hotel and Casino, Vance said Harris was scolding Trump supporters.

"She was like, how can you dare have a sense of humor about American politics? It's one of the things I love about my running mate is he does have a sense of humor. You can fix the country but have a good time while you're going around and campaigning across the United States, right?" Vance said.

Harris has recently revived one of President Joe Biden's key campaign attacks: that Trump represents a threat to democracy.

-ABC News' Hannah Demissie

Republicans are warning that they could get vastly outspent in the battle for state legislative races across the country, a continuing reversal from last decade's elections, when the GOP dominated such contests.

In a donor memo first reported by Politico and obtained by ABC News, Republican State Leadership Committee President Dee Duncan wrote to donors that his group's historic $44 million investment in state legislative races this year would pale in comparison to the $175 million its Democratic counterpart and allied liberal groups planned to dish out.

"Since the…aforementioned national liberal outside groups have already combined to spend at least $69 million of traceable money across the country, that means they are on the road to dump at least another $100 million into key races between now and November," Duncan wrote in his call to action.

"We don't expect to fully close the fundraising gap we face, but additional resources are still immediately needed to counter the opposition's massive spending advantage in these final weeks to ensure we remain on course to defend our majorities and seize any and all opportunities to flip chambers still within reach," he added.

Democrats have made a concerted effort to get off the mat in state legislature races across the country. In 2022, the DLCC was able to overwhelm the RSLC in spending in the final weeks, a scenario Duncan specifically referenced as wanting to avoid this time around.

After having their ranks decimated in the 2010 midterms and struggling for over a decade to recoup, voting and abortion restrictions pushed by Republicans helped underscore the importance of such bodies for voters, producing an influx of funds that have helped Democrats go on offense. This year, the Democratic National Committee sent a first-of-its-kind $2.5 million to the DLCC.

Democrats are now on offense in Arizona, New Hampshire, Wisconsin and the Pennsylvania Senate, where they're seeking to flip state chambers. Republicans are working to regain ground in Michigan and Minnesota, as well as in the Pennsylvania House.

Harris swiped at Trump's past comment about being a dictator only on "Day One" and his more recent threat to use the military against political opponents.

"Donald Trump is increasingly unhinged and unstable," she said. "And in a second term, people like John Kelly would not be there to be the guardrails against his propensities and his actions. Those who once tried to stop him from pursuing his worst impulses would no longer be there, and no longer be there to rein him in."

Harris did not take any questions after she finished the brief remarks.

Harris, speaking at the vice president's residence, hammered Trump after his former chief of staff John Kelly's bombshell comments to the New York Times.

Kelly claimed Trump said he wanted generals like the ones Adolf Hitler had, and that, in his view as a retired general, the former president fell under the definition of a "fascist."

"It is deeply troubling and incredibly dangerous that Donald Trump would invoke Adolf Hitler, the man who is responsible for the deaths of 6 million Jews and hundreds of thousands of Americans," Harris said. "All of this is further evidence for the American people of who Donald Trump really is."

"The bottom line is this. We know what Donald Trump wants. He wants unchecked power," Harris added. "The question in the next 13 days will be: What do the American people want?"