Joe Biden has embarked upon an eight-day “no malarkey barnstorm” bus tour across Iowa as the former US vice-president attempts to arrest his flagging poll numbers in the key state, which is the first to vote in the race to be the Democratic 2020 presidential nominee.

Biden started his election blitz on Saturday, telling supporters in a fundraising email that he was undertaking an “eight-day, 18 county, ‘no nalarkey’ barnstorm” across Iowa. “The plan is to meet as many caucus-goers as I can, and we’re going to cover a lot of ground to do it,” the email read.

On Sunday, the former vice president was due to attend a meet-and-greet in Carroll, a town hall in Storm Lake, meet and greets in Jefferson and Perry, and a town hall in Spencer.

Fired up and ready to go for the #NoMalarkey barnstorm! pic.twitter.com/4lpU7waqzh — Joe Biden (@JoeBiden) November 30, 2019

The bus tour follows recent polling that shows Biden’s standing has slipped among Democratic voters in Iowa who, on 3 February, will be the first caucus in the US to pick a favored candidate to take on Donald Trump in the 2020 presidential election.

After topping the Democratic field in the state in several polls as recently as September, the 77-year-old has seemingly been eclipsed by Pete Buttigieg in recent surveys of Iowan Democrats. Still, the polls show a tight race and Biden’s supporters deny that his campaign is in any sort of trouble, especially as he still frequently leads the Democratic field in national polls.

“As people get closer and closer to February, they become more and more practical about this,” said the former Iowa governor Tom Vilsack, who recently gave Biden his most high-profile Iowa endorsement. “He can make the strongest case, among all the candidates, that he is in a position to get things done, and he is in a position to win.”

Biden opened November with an underwhelming speech at the state party’s “Liberty & Justice” gala. While Buttigieg and Senator Elizabeth Warren roused thousands of supporters in a Des Moines arena, Biden ticked through his standard applause lines as whole sections of seats purchased by his campaign sat empty.

In south-east Iowa, the state party’s rural caucus vice-chairman says Biden’s footprint isn’t visible. “I know the names of the people who are supporting various other candidates,” Glenn Hurst said. “But in terms of people out there knocking on doors, who attend other campaign events, district events, I can’t name a member of the south-east Iowa Democrats who’s supporting Joe Biden.”

Fairly or not, Biden’s national staff has fueled skeptical assessments with pronouncements that he doesn’t have to win Iowa to win the nomination.

Iowa is overwhelmingly white; Biden’s national advantage leans heavily on non-white voters who help determine outcomes in Nevada, South Carolina and many 3 March Super Tuesday states.

Yet all the handwringing misses key variables in Iowa, according to Vilsack and other Biden supporters.

They contend that, public enthusiasm aside, Biden has the broadest range of support both demographically and geographically, especially in rural and small-town Iowa and among the growing minority population that, while small, could prove important with so many candidates dividing the overall caucus vote.

Those Biden organizers that get so much criticism, the campaign says, spend their days not with local party officials, but with volunteers knocking on doors and making calls. Their focus: reliable caucus participants, plus disaffected Republicans and independents.

“The media seems to have picked up this narrative that the Biden campaign is not doing well or not as well as it should,” said the longtime party activist and Biden supporter Phyllis Hughes Ewing, daughter of a former Iowa governor and US senator.

“I’m on the phones with voters two nights a week for several hours at a pop. I’m a boot on the ground, and that’s not what I’m seeing.”