Former Vice President Joe Biden suggested Wednesday in Iowa that he thinks he's still current Vice President Joe Biden, telling an Iowa reporter about environmental tax credits that 'the president and I' jointly want to put in place.

Rattling off a litany of green initiatives he wants to see rural America embrace, Biden said offering federal tax incentives would help nudge the nation toward a carbon-neutral future.

'It would also help people with housing, if you were able to continue to have what we propose, and I propose, what the president and I—' he said, before stopping himself.

He continued a second later, saying Americans should 'have, you know, tax credits for insulating homes, tax credits for making all businesses – all buildings, you know – energy contained, et cetera.'

A Republican operative in Iowa reacted Friday afternoon, saying: 'Poor Joe. He thinks he still has Mike Pence's job! He's definitely not getting Donald Trump's.'

Former Vice President Joe Biden is falling fast in Iowa, and now sits in fourth place among Democratic White House hopefuls in a new New York Times Upshot/Siena College poll

A confused Biden said Wednesday in the Hawkeye State, speaking in the present tense, that 'the president and I' – presumably a reference to Barack Obama – 'want' a package of environmental-minded tax credits for new buildings

Biden spoke at Loras College in Dubuque, Iowa – in a state where his popularity among Democrats has slipped beneath that of South Bend, Indiana Mayor Pete Buttigieg. The former VP is now in fourth place in the Democratic primary contest, according to a New York Times Upshot/Siena College poll released Friday.

Massachusetts Sen. Elizabeth Warren is leading the field with 24 per cent, followed by Vermont Sen. Bernie Sanders with 19 and South Bend, Indiana Mayor Pete Buttigieg with 18. Biden has 17 per cent backing among likely Iowa Democratic caucusgoers.

'I think American agriculture should be the first zero-emitter of carbon in America,' he declared Wednesday, speaking backstage to a reporter from the Dubuque Telegraph Herald. 'And it's possible to do that and create jobs at the same time.'

A video of the brief interview on the newspaper's YouTube channel had been played just 104 times by Friday afternoon.

Biden, once a 2020 front-runner, has taken incoming fire from President Donald Trump on his right and more liberal Democrats on his left.

Trump has pilloried 'Sleepy Joe,' as he calls him, for allegedly using his position while vice president as leverage to create lucrative foreign business opportunities for his son Hunter.

Biden was known for inappropriate political gaffes including the buddy-movie moment in March 2010 when he told President Barack Obama on an open microphone that signing the Affordable Care Act was 'a big f***ing deal'

Those, Trump has claimed, included a $1.5 billion Chinese investment for a fund in which he held a 10 per cent stake, delivered following a father-and-son trip to Beiing aboard Air Force Two.

Trump has also blasted Biden for boasting that he used $1 billion in U.S. loan guarantees to force Ukraine into firing its top prosecutor Viktor Shokin, a man considered corrupt by most international bodies. Shokin was also investigating Burisma Holdings, a company where Hunter Biden was paid handsomely for sitting on the Board of Directors.

Democrats in the first primary debates have cast Biden as insufficiently progressive, contrasting their full-force proposals to nationalize medical care with his comparatively moderate position.

Biden has attracted other slings and arrows for continuing his decades-long habit of gaffes and mental slips when he speaks to voters.

During an August 28 event in South Carolina, he complained that Trump had laid the blame for Russia's 2014 Ukraine military incursion at the previous administration's feet.

Russia 'invaded another country and annexed a significant portion of it called Crimea,' Biden said.

'He's saying that it was president — my boss — [that] it was his fault,' he continued, stumbling when he tried to recall Barack Obama's name.

On Thursday he confused the Paris Climate Treaty with the Paris Peace Accord, the 1973 armistice that ended the Vietnam War.

'I'm going to make sure that we rejoin the Paris Peace Accord on day one,' Biden said, forecasting his Inauguration Day.

Biden has run for president twice before, in 1988 and 2008, and is now 76 years old; he would be the oldest-ever U.S. president if he were elected

Biden led in Iowa Democratic polls for 2020 by an average of 13 points last December but has slowly given way to Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders

President Trump has withdrawn the United States from the climate treaty, saying it needlessly disadvantages the American economy to the benefit of China and other trade rivals.

During last month's Democratic debate, Biden mangled his argument about the 'unfair' disparity between income tax rates and the lower rates paid on investment capital gains.

As millions watched, he confused the stock market with a supermarket.

'Why should someone who's clipping coupons in the stock market may, in fact, pay a lower tax rate than someone who in fact is, like I said, a schoolteacher and a fireman?' Biden asked.

'It's ridiculous.'