The US vice presidency was famously compared to a “warm bucket of piss” by FDR’s first veep.

But JD Vance is more likely thinking buckets of champagne on ice — and so are fans of Trump’s economic populism.

Vance is well known on Wall Street and Silicon Valley.

He worked in venture capital after graduating from Yale Law School.

In his bestselling memoir “Hillbilly Elegy,” he wrote about the economic and social despair of the Rust Belt.

He has since spent two years in the US Senate.

Years ago, he was a free-market man who believed foreign investment in the US helped save his Ohio factory town.

He was no fan of Donald Trump’s nationalism, particularly on the economy.

But something changed with Vance after his memoir hit in 2016.

Many hardcore liberals became conservative after being mugged by reality.

Vance’s mugging led him into economic populism — tariffs, a weak dollar, trade recriminations — away from free markets toward Trump populism.

It propelled him to the US Senate with Trump’s blessing after they patched things up, and now maybe the vice presidency.

Wednesday night, the American people will hear from him first hand as he speaks at the GOP convention in Milwaukee.

It propelled him to the US Senate with Trump’s blessing after they patched things up, and now maybe the vice presidency.

In Vance, Trump might well be signaling that in a second term he’s going full-on MAGA and passing the torch to someone with capable hands to carry out this agenda (though you never really know with The Donald, as I will explain).

True, Vance has been in the Senate for just two years, but he’s made his mark through his clear explanation of Trump-styled populism.

Trump picked maybe the most articulate spokesman of MAGA economics.

Recall: Trump economic populism was much more inchoate when he was first elected president, and in many ways it got softened by Trump’s selection to kill key economic advisory roles, supply siders, traditional conservatives and business types in key economic posts, including Mike Pence, Larry Kudlow, Gary Cohn and Steven Mnuchin.

He recently blurted out to Bloomberg he would consider a globalist’s globalist JP Morgan CEO Jamie Dimon as Treasury Secretary.

Yes, The Donald has proven to be a somewhat heterodox economic populist, and it worked.

Those folks helped craft an economic agenda that led to tax cuts, deregulation that softened the economic blow from his trade war policies as other countries retaliated.