Hillary Clinton’s campaign workers at the Orpheum Theatre busily sign up supporters to commit their vote to the Democrat in the first nominating contest of the 2016 presidential election on February 1st.

Her team circulate around the foyer outside the main theatre in Sioux City in western Iowa near the border with Nebraska and South Dakota.

They are taking names among the crowd before the candidate takes the stage for a “town hall meeting” on Tuesday afternoon.

Outside, on the street, they brave freezing temperatures to sign up supporters there too.

This was one of six events on a two-day Clinton “River to River” visit to Iowa covering towns from the Mississippi on the midwest state’s eastern border to the Missouri on its western frontier.

There is an energy about the take-nothing-for-granted approach that Clinton, the Democratic presidential frontrunner, and her campaigners are adopting in this electorally important state.

There is, after all, just four weeks before voters pick their preferred candidate to be president in Iowa’s famous caucuses.

Clinton’s appearance in Sioux City was her 79th in Iowa since declaring her presidential candidacy in April 2015.

"I know in my heart that this caucus is going to be historic, but it is going to take all of you, all of us together to reach out to our friends, neighbours, family members to talk to them, to get them to commit to caucus," said Penny Rosfjord, a Clinton supporter and Iowa precinct captain, before introducing the candidate at the campaign event.

Clinton kicked off the meeting with a heartfelt plea for supporters to be part of her “get out the caucus” team in Iowa, a state where typically only one in every five Democrats takes part in a caucus.

“We want to do really, really well here,” she said, peppering her speech with “talk to your friends and neighbours” and “remind your friends” as she presents her manifesto of policies to a receptive crowd.

Learned a lesson

The 68-year-old former secretary of state has learned a lesson from her first, failed presidential bid when she came third in Iowa in 2008, well behind then senator

Barack Obama

.

Despite a comeback win in the second-nominating contest, the New Hampshire primary, Clinton never really recovered after that definitive loss to Obama in Iowa.

This time around, opinion polls put Clinton on average at 53 per cent nationally, 21 points ahead of self-professed democratic socialist senator Bernie Sanders, and almost 50 points ahead of former Maryland governor Martin O'Malley.

Clinton’s lead over Sanders is tighter in Iowa, at 49.8 per cent to 37 per cent for the independent Vermont senator.

“She needs to end up in the high 50 per cent range, if not better. If Sanders is fairly close to her in Iowa, say 52-48 or somewhere there, I think that’s a bit of an embarrassment for her,” said Dennis Goldford, a politics professor at Drake University in Des Moines, Iowa.

“She needs a strong finish to put to rest any kind of challenge because right now he seems to be leading in New Hampshire so she needs to be build herself a little protection against that possibility.”

Sanders’s populist progressive appeals to Clinton supporters, as it has to hundreds of thousands of young Democrats in his surging campaign over the past nine months.

For Hillary fans at the Orpheum, it comes down to electability in the November general election.

“I support Bernie. I think he’s a great guy,” said Barbara Schaap, a Clinton supporter from Alden, Iowa, watching from the balcony.

“I side with him on a lot of issues but I am afraid that if it would come to him and some Republican, there’s going to be too many people that automatically see the word socialism and just freak out.”

Clinton’s pitch to voters is simple: America does better when there is a Democrat president and she is the right Democrat to be the next president.

She casts herself as a champion of left-behind middle-class Americans as well as a natural and experienced successor to the last two Democrat presidents, her husband and Barack Obama, in whose cabinet she served for his first term in the White House.

Lambasting Republicans

Both

Bill Clinton

and Obama inherited recessions from Republican presidents, she told the crowd.

Obama doesn’t get the credit he deserves “for digging us out of that deep hole we found ourselves in” and for creating 13 million jobs.

Her husband created 23 million new jobs in eight years, she said, and incomes went up for everyone, not just the rich.

“For me, that’s exhibit A,” she said before lambasting Republicans for policies that would mark a return to trickle-down economics.

“I used to be a trial lawyer and I learned early on that if you got the law on your side, you argue the law.

“If you have the facts on your side, you argue the facts. If you don’t have the law or the facts, you pound on the table.

“We have a lot of table-pounders running for president on the Republican side.”

Clinton ticked off a list of progressive policies: improving the Obamacare health insurance scheme, reducing the cost of drugs, introducing early childhood education, affordable college education and paid family leave, and supporting Obama’s executive actions this week to cut off the ready availability of guns to criminals.

She adds to her proposals for stopping American corporations using overseas companies to play “gimmicky tax games”, agreeing with a questioner in audience who suggests that she uses patents as leverage to make companies such as tech giant Apple pay more taxes at home.

One of the more muted responses from the Sioux City crowd was Clinton's call for comprehensive immigration reform, perhaps explaining the public appetite that the Republican frontrunner Donald Trump has tapped.

“My biggest thing is I don’t have a problem with someone coming here but you do it the legal way,” said Don Barnes from Sioux City, a member of a carpenters’ trade union, who was holding a Clinton sign.

“If you don’t do it legally, then you don’t need to be here. Don’t be a drain on our system.”

Clinton, who rarely mentions her Democratic rivals on campaign events unless asked about them, had no problem criticising Sanders when questioned about the biggest contrast with her closest rival.

“I think I have a broader, more comprehensive set of policies about everything including taking on Wall Street,” she said, before criticising the Vermont senator’s plan to break up “too big to fail” banks which he launched at a campaign event in New York, also on Tuesday.

Sanders wants to reinstate a version of the Glass-Steagall Act, a Depression-era law that banned commercial banks engaging in risk investment banking.

The law was repealed during Bill Clinton’s presidency, which Sanders happily pointed out.

Alternative plan

Clinton said her alternative plan – to break up big banks if they pose a risk to the financial system – had the support of the likes of former congressman

Barney Frank

, a co-architect of post-financial crisis regulations, and economist

Paul Krugman

.

To her audience, Clinton presents herself as a pragmatist with first-hand knowledge and executive experience to the ideologue in Sanders.

“I am a progressive who likes to get things done and I will get into that White House. I don’t need a tour. I know where the Oval Office is,” she said in her closing remarks at the Orpheum to cheers.

Iowans will hear much more on the Clinton versus Sanders contest over the coming days.

Bill Clinton is making his second solo appearance on his wife’s campaign when he travels to Iowa today after his debut in New Hampshire on Monday.

Sanders starts a four-day swing through Iowa tomorrow.

The frequency of the visits to this state in preparation for the first 2016 election test shows, as Clinton put it in Sioux City, how high the stakes are.