The author turned Ohio Senate candidate JD Vance has blamed America’s woes on “the childless left”, singling out Vice-President Kamala Harris, transportation secretary Pete Buttigieg, Senator Cory Booker and Congresswoman Alexandria Ocasio-Cortez for their own share of the blame.

Speaking to a conservative thinktank, the Republican also praised the far-right president of Hungary, Viktor Orbán, for encouraging married couples to have children.

Vance is a venture capitalist and former US Marine who wrote the bestseller Hillbilly Elegy about his upbringing in Appalachia and experience studying law at Yale.

Running for a Senate seat which will be vacated next year by Rob Portman, a relative centrist in a party dominated by Donald Trump, Vance has attracted backing from the tech billionaire Peter Thiel. He has also apologised for tweets criticising Trump, for whom he has said he did not vote in 2016.

On Friday night, Vance spoke to a conference organised by the Intercollegiate Studies Institute.

The “childless left”, he said, have no “physical commitment to the future of this country” yet offer an “elite model” for the American business and political class.

Mentioning the four prominent Democrats, he asked: “Why is this just a normal fact of … life for the leaders of our country to be people who don’t have a personal and direct stake in it via their own offspring?”

Kamala Harris has two stepchildren with her husband, first gentleman Doug Emhoff, who are known to call her “Momala”. Buttigieg has no children with his husband, Chasten Buttigieg. Booker and Ocasio-Cortez are in relationships but are not married and do not have children.

“The Democrats are talking about giving the vote to 16-year-olds,” Vance said. “Let’s do this instead. Let’s give votes to all children in this country, but let’s give control over those votes to the parents of the children.

Asking if such a move would “mean that non-parents don’t have as much of a voice as parents” and “that parents get a bigger say in how democracy functions”, Vance said that though he expected criticism from “the Atlantic and the Washington Post and all the usual suspects”, the answer was yes.

“We should worry that in America, family formation, our birth rates, a ton of indicators of family health have collapsed,” he said, warning of a “civilisational crisis”.

In Hungary under Orbán, Vance said, “they offer loans to newly married couples that are forgiven at some point later if those couples have actually stayed together and had kids.”

“Why can’t we do that here? Why can’t we actually promote family formation?”

In response, Dave Weigel, a Washington Post reporter, tweeted that Vance should “pretend I’m not here”. He added: “Interesting speech. Vance praised a policy by Viktor Orbán that pays parents who have multiple children … but didn’t mention the Democrats’ child tax credit.”

This month, under Covid relief measures, the Biden administration is beginning distribution of income-determined tax credit payments to parents which average $423 a month and are due to continue for a year.

George Conway, a lawyer and prominent Trump critic, was short and to the point.

Vance, he said, is “a Yale Law School graduate and knows this is stupid”.