Joe Biden made his most recent gaffe on Sunday when he told a crowd at a campaign event in New Hampshire that they were actually in Iowa.

'What you do here in Iowa,' Biden said to supporters in Nashua, New Hampshire before quickly correcting himself. 'What they do in Iowa, what you do here in a primary in New Hampshire, is going to set the tone for who is likely to be the nominee for president of the United States.'

Biden's slip up happened just one day after he concluded his eight-day 'No Malarkey' bus tour across 18 Iowa counties, which the candidate announced the day of the Democratic debate in Atlanta, Georgia last month.

It appeared that Biden also confused his campaign event guest, Former Secretary of State John Kerry, who also mixed up the the first primary state and first caucus state his remarks.

Joe Biden continued his pattern of gaffes on Sunday when he confused which state he was in, telling supporters in New Hampshire that they were in Iowa

His mix-up came the day after he concluded his eight-day 'No Malarkey' tour through 18 Iowa counties

Biden appeared to confuse his guest former Secretary of State John Kerry, who endorsed him last week. He said when talking about climate change that American needs 'to make Iowa a place where you actually become the Saudi Arabia of wind power'

When referring to the 'existential' crisis of climate change, he said there is a need 'to make Iowa a place where you actually become the Saudi Arabia of wind power.'

'New Hampshire,' Kerry continued, 'producing the technologies, maybe even the negative emissions technologies, where we take carbon dioxide out of the air, and put it to a use.'

Kerry endorsed Biden last week.

This isn't the first time the former vice president has mixed up U.S. states.

While speaking to voters at a fish-fry in Cedar Rapids, Iowa in early November, Biden claimed he was in Ohio.

'How many unsafe bridges do you still have here in the state of Ohio?' Biden asked a group of Iowans. 'I mean Iowa, and I was just in Ohio because they have more.'

Biden was in Columbus, Ohio at the end of October for the fourth round of Democratic primary debates.

Over the summer, Biden also confused New Hampshire for the neighboring New England state Vermont.

'I've been here a number of times,' he told reporters in New Hampshire. 'I love this place. Look, what's not to like about Vermont in terms of the beauty of it? And what a neat town, this is sort of a scenic, beautiful town and everyone has been really friendly. I like Keene a lot.'

He has mixed up states in the past. While in Iowa, Biden claimed he was in Ohio and during a stop over the summer in New Hampshire he said while speaking to voters that they were in the neighboring state of Vermont

Mixing up states, some supporters assert, is easy when traveling across the country on the campaign trail – but none of Biden's 14 Democratic competitors seem to have quite the same issue, even though several have just as grueling campaign schedules.

Confusing Iowa and New Hampshire for different states could hurt the presidential hopeful as those two early voting and caucus states help set the stage for the primary elections.

Biden's recent increased efforts in the two states comes as South Bend, Indiana Mayor Pete Buttigieg surged in regional polls.

In November he beat out all of his Democratic competitors in both Iowa and New Hampshire, clenching the No. 1 spot in two separate polls. He also finally broke double-digits in national polling at the end of November.

Biden has been steadily slipping in polling numbers and has lost his front-runner status in several surveys in the past few months – his continued gaffes haven't helped his hand.

The Atlantic published an article this month by a writer who stutters, claiming that Biden's gaffes and at-times confusing speaking style can be attributed to his boyhood stutter, which the 2020 candidate as talked about throughout his political career.

But it's unlikely that him mixing up different states could be excused away by his past stuttering issues.

Biden claims he makes mistakes on the campaign trail because he's exhausted.

'I don't think of myself as continuing to stutter,' Biden told 'Axios on HBO' when asked about the claims of regarding his stutter. 'That doesn't cross my mind – that I'm stuttering.'

'Look, the mistakes I make are mistakes. And some people think I still stutter. I don't think of myself that way,' he said in the interview last week in Iowa.

'I'll find myself searching for a second,' Biden continued, claiming he can't find the right words sometimes. 'I've always attributed that to being tired and not to the stutter.'