Election officials faced relentless pressure from former President Donald Trump and his supporters to overturn his defeat in the 2020 poll, a congressional panel has heard.
Elected Republicans as well as poll workers say they were threatened.
A Georgia vote counter said she was forced to temporarily leave her home, while an Arizona official said protesters called him a paedophile.
The House of Representatives panel accuses Mr Trump of an attempted coup.
The select committee has conducted a nearly year-long investigation into how Trump supporters invaded Congress on 6 January 2021 to disrupt lawmakers as they certified Democrat Joe Biden's election victory.
Mr Trump has stood by his disproven claim he only lost the 2020 presidential vote because of fraud, and has dismissed the panel as a political witch hunt.
On Tuesday, in the fourth public hearing so far, the panel heard from election workers in the states of Arizona and Georgia. Mr Biden defeated Mr Trump in both states, which had previously backed Republicans for the White House.
"We received... in excess of 20,000 emails and tens of thousands of voice mails and texts, which saturated our offices and we were unable to work, at least communicate," said Rusty Bowers, speaker of the Arizona House of Representatives.
The witness - who campaigned for Mr Trump in 2020 - said the threats and insults have continued with protesters outside his house attempting to smear him as a paedophile.
"It was disturbing, it was disturbing," Mr Bowers said.
He recalled Trump lawyer Rudy Giuliani at one point telling him: "We've got lots of theories, we just don't have the evidence."
The panel also heard testimony from Shaye Moss and her mother, Ruby Freeman, who became the targets of conspiracy theories in their jobs as election workers in Fulton County, Georgia.
Although Mr Biden won the state by nearly 12,000 votes, Mr Trump and his supporters spread unfounded claims of mass voter fraud.
In recorded messages, Mr Trump had called Ms Moss "a professional vote-scammer and hustler", alleging the mother-daughter duo cheated to help Democrats.
"I've lost my name, I've lost my reputation, I've lost my sense of security," Ms Freeman said through tears, in video presented by the committee on Tuesday.
"Do you know what it feels like to have the president of the United States target you?"
Ms Moss said she faced "a lot of threats wishing death upon me", and that the harassment - including racial abuse - had "turned my life upside down".
Ms Moss said she was forced to move home for two months, has gained about 60lb (27kg) in weight and is now reluctant to leave the house at all.
She told the committee that Trump supporters had visited her grandmother's home, looking for her and hoping to make a "citizen's arrest".
Republican Georgia Secretary of State Brad Raffensperger described a notorious phone call from Mr Trump in which he was asked to "find 11,780" votes that would hand him victory in the state.
"We just followed the law and followed the constitution," he said. "At the end of the day, President Trump came up short."
He said that Trump's legal team alleged more than 10,000 dead people voted, but a review found a total of only four.
His top aide, Gabriel Sterling, told the committee that fighting the election scam claims "was like a shovel trying to empty the ocean".
The hearings have attempted to tie the former president directly to the efforts to overturn the election.
At Tuesday's hearing, the committee chairman Bennie Thompson, a Democrat, said: "A handful of election officials in several key states stood between Donald Trump and the upending of American democracy."
His deputy on the committee, Liz Cheney, a Republican, said: "We cannot let America become a nation of conspiracy theories and thug violence."