The campaign advertisement was released on Thursday by Ms Cheney's re-election campaign, two weeks before a Republican primary in Wisconsin that the January 6 committee vice chairwoman is expected to lose by a wide margin. Echoing the warnings of his daughter, Mr Cheney said Mr Trump's continued false claims about the 2020 election are a danger to the US.
“In our nation’s 246-year history, there has never been an individual who is a greater threat to our republic than Donald Trump,” Mr Cheney said.
“He tried to steal the last election using lies and violence to keep himself in power after the voters had rejected him.
“He is a coward. A real man wouldn’t lie to his supporters. He lost his election, and he lost big. I know it, he knows it, and deep down, I think most Republicans know it.”
Ms Cheney has been a frequent target of Mr Trump since she and nine other Republicans voted to impeach him for his role in the January 6, 2021 attack on the US Capitol. The former president endorsed her primary challenger, lawyer Harriet Hageman, who has repeated Mr Trump's claims that the 2020 election was rigged.
In January, Mr Cheney and his daughter were the two lone Republicans to attend a US House session on the anniversary of the attack on the Capitol.
Mr Cheney praised his daughter in the new campaign video for “standing up for the truth, doing what’s right, honouring her oath to the constitution, when so many in our party are too scared to do so”.
Mr Cheney served as vice president under George W Bush from 2001-2009, when he held considerable influence over American foreign policy. He was a key architect of the Iraq war and a champion of the CIA's use of torture in the early years of America's “war on terror”.