Money was always going to be central to these midterms. With control of congress at stake – and with it perhaps the future of Donald Trump – there was no doubt that dollars would flow.

The non-partisan Centre for Responsive Politics, projects more than $5.2bn will be burned through this election cycle, making it the most expensive midterm by some margin. With a handful of days to go, $4.7bn has been spent by candidates, parties or Political Action Committees (PACs). The centre estimates Democrats will spend $2.53bn and Republicans $2.19bn. Independents and other parties will spend $460m.

“The significance of this election is clear. But whether it’s a blue wave or a red wave, one thing is certain: a wave of money is surging towards election day, much of it coming from the wealthiest donors targeting this year’s most competitive races,” says Sheila Krumholz, the centre’s executive director.

For the Democrats, the toughest piece of the puzzle has been using that money to connect its deep blue pools of support on either coast, with the less densely concentrated numbers in the heartland. It hopes to win races in seats long considered safe Republican turf.

Illinois congresswoman Cheri Bustos wants to be that bridge. Bustos, whose district includes the city of Peoria, the name of which has entered American culture as a shorthand for mainstream ordinariness, says issues there are as equally relevant to the supporters of progressives such as New York’s Alexandria Ocasio-Cortez, as they are to those of Paul Davis, the son of an elementary school teacher who is contesting the Kansas 2nd.

“We’re focused in Peoria on the same kind of things folks in New York City or Chicago or LA are focused on, which is to make sure people can do well by their families,” the Democratic Congressional Campaign Committee’s (DCCC) chair of so-called heartland engagement tells The Independent.

She adds: “What we hear all across this country is that health care costs too much. They’re concerned if they have a child with cerebral palsy… they’re not going to be able to get health insurance. They want us to do more about raising people’s wages.”

The Democratic Party has long struggled over how progressive its platform and message should be, an often bitter fight that most recently erupted in the 2016 primary race between Hillary Clinton’s support for incremental change and Bernie Sanders’ more radical vision. In a system in which only two parties have a realistic chance of winning a national seat, along with a handful of independents, those parties are obliged to try and have broad arms.

Bustos says the Democrats have an “image problem” but can overcome this by engaging directly with people. In 2016, Clinton was criticised for spending too little time addressing concerns of working class voters, especially in places such as the midwest, some of whom previously voted for Barack Obama, but decided that year to vote for Donald Trump and his promise to “make America great again”.

Bustos, one of just 12 Democrats who won in districts where Trump beat Clinton, said no special skills were were required to engage with voters in parts of the nation often derisively referred to as the “flyover states”.

“It takes hard work and going to towns that might just have 300 people or 800 people, and listening to those folks,” says the 57-year-old. “And make sure, whatever it is people at home have shared, that we come back out to Washington and write legislation that relates the needs at home, and vote for legislation that reflects the needs at at home.”

US midterm elections: the voters Show all 10 1 /10 US midterm elections: the voters US midterm elections: the voters Ross Kershey of Exton, Pennsylvania objects to President Trump's recent threat to unilaterally suspend the constitutional protection of birthright citizenship as a way to control undocumented immigrants AP US midterm elections: the voters Thomas Jakel of Eveleth Minnesota is a former miner. The economy is the most important thing to voters in his town AFP/Getty US midterm elections: the voters Jerry Mcneff of Exton, Pennsylvania intends to split his ballot between the parties for Pennsylvania's House, Senate and governor elections AP US midterm elections: the voters Jean Hoffman of Exton, Pennsylvania has concerns about the cost of her daughters' college education. She thinks that voting Republican might help extend the economy's rise AP US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters US midterm elections: the voters Supporter Jenny Haley and son wait in line to see a Trump Rally in Rochester, Minnesota AFP/Getty US midterm elections: the voters Dick Calef of Exton, Pennsylvania is a life-long Republican. He credits the economic gains in suburban Philadelphia to longer-term factors beyond Trump's policies, such as the growth of internet and health care companies. He's not yet sure how he will vote AP US midterm elections: the voters Markus Fasel of Mendota Heights, Minnesota attends a campaign event for Democrat Angie Craig, his favoured congressional candidate AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters

Lots at stake

Political commentators frequently describe upcoming elections as being unusually crucial. Yet, there is wide agreement a lot is at stake on 6 November. Voter enthusiasm is high, and turnout, usually much less in midterms than in presidential elections, is likely to be big.

With the White House and both houses of congress in the hands of Republicans, Democrats are desperate for a win. Their best chance is the House of Representatives, where they need to flip 23 seats, and which is where any impeachment proceeding against Trump would start.

The political analysis website FiveThirtyEight believes the Democrats have a six out of seven (84.6 per cent) chance of taking the house, and the Republicans just a one out of seven chance of holding it (15.4 per cent). It gives an opposite prediction for the senate, suggesting Republicans have a six out of seven chance of retaining it.

Mike Fraoili, a veteran Democratic strategist said he “could not see how”, Republicans could hold on to the house.

“I believe voters out there believe they want a check on president Donald Trump,” he says. The most important factor in ensuring a victory was getting people to vote – everybody from “millennials to seniors and everybody in between.”

US Midterms 2018: The five big questions

PAC Man

Jeb Fain is a spokesman for the House Majority Political Action Committee, which is closely associated with minority leader Nancy Pelosi and which raises and spends millions of dollars on candidates across the country. Mr Fain declined to say how much it expected to spend in 2018, but said it “expected to exceed the roughly $50m” it spent two years ago.

PACs are supposed to enforce a firewall between their fundraising and particular candidates. In reality that is sometimes not the case. Fain said his organisation determined which races to spend on, and which issues to highlight.

Yet his message was similar to that of Bustos and other mainstream Democrats. “Our messaging has been remarkably consistent. We have been focused on healthcare and taxes going back a year-and-a-half…That is what the Democrats have been focused on. The Republicans have been doing a lot of personal stuff and nasty stuff and I think it shows a degree of desperation.”

The DCCC’s GOP equivalent, the Republican National Congressional Committee, failed to respond to requests to talk about the campaign.

Matt Fleming, a spokesman for the California Republican Party, said he was confident of holding onto seats such as those in Orange County, that Democrats were spending huge sums on to try and flip. “Holding every seat in the state is important if we are going to have any chance of stopping the Democrats’ radical, expensive agenda,” he says.

The battle for the US House of Representatives, 2018 (The Independent)

Wave of women

Analysts believe 2018 could see a record number of women elected to congress – perhaps more than 100 – with almost all the new faces coming from the Democrats.

Huge sums have been spent on races such as the Minnesota 2nd, where Democratic Angie Craig is seeking to oust Republican Jason Lewis. Democrat Stacey Abrams is the first African American woman nominated by a major party for a governorship race. She is competing in Georgia with a progressive platform. Ayanna Pressley is set to be the first black woman elected to congress from Massachusetts after winning the Democratic primary. Since then, she has run unopposed.

A major funder and supporter of Democratic women is the group EMILY’s List. They are confident of taking back the house.

“We really believe we have a lot of opportunity in the House of Representatives to make sure we add a historic number of Democratic women,” says president Stephanie Schriock. “The house also needs to be in Democratic hands so we can hold this Trump administration accountable.”

Away from the mainstream Democratic organisations, smaller groups have also been spending to try and ensure candidates that support a progressive platform, such as a $15 minimum wage, are elected.

Justice Democrats, established by people who worked in the 2016 Sanders campaign, endorsed and supported almost 80 candidates. Of those, 26 have made it to the election on Tuesday.

The candidates all share a commitment to a progressive platform that includes Medicare for All, investment in renewable energy and the scrapping of ICE, the Immigration and Customs Enforcement that it describes as a “state-funded terror group that regularly violates basic human rights”.

Spokeswoman Nasim Thompson says all its candidates represent both authenticity and a positive message. She said the party establishments had created a vacuum for groups that wanted to back candidates more in touch with voters.

Among its candidates are New York’s Ocasio-Cortez, and Ilhan Omar, who is contesting the Minnesota 5th and would become one of the first Muslim women elected to congress if she wins. (Another Muslim woman, Rashida Tlaib, is tipped to win Michigan’s 13th.)

“We see it as a difference between the bottom and top, more than right and left,” she says.

Bustos, who tries to spend as much time as possible talking to people, at grocery stores and workplaces, will campaign to join the Democratic leadership team as assistant Democratic leader if the party wins next week.

She and other Democratic leaders have faced grassroots’ criticism for not supporting more progressive candidates. Some have criticised Pelosi for not pushing for the impeachment of Trump, after the leadership decided such a tactic could backfire.