“We’re in a fight for the soul of America,” was how former US Vice President Joe Biden summed it up earlier this week. 

Few Americans, Democrats especially, are under any illusions as to what is at stake in this coming Tuesday’s midterm elections. 

As history is testament, there have been some pretty dramatic midterms in the past. A certain Republican landslide back in 1994 that changed the course of Bill Clinton’s presidency especially springs to mind. 

Even the likes of that though, pales alongside the potential significance of next week’s poll, which is in effect, a dress rehearsal for what will be one of America’s most consequential White House races two years from now.

According to the latest opinion polls with just three days until the ballot, indications are that the Democrats after two years of wielding no practical political power in Washington, are poised to take control of the House of Representatives, and the Republican Party will retain its narrow majority in the Senate and possibly even expand it.

For the Democrats taking a majority in even one of the chambers on November 6 would give them a chance to more effectively oppose Republican US President Donald Trump’s agenda, as well as potentially launch investigations into his administration.

Many races across the country, however, appear to be really close, which means both parties are in for a nerve jangling few days and substantial uncertainty still surrounds the outcome. 

Currently Republicans hold a 23-seat majority in the 435-seat House, far wider than their two-seat majority in the 100-seat Senate, but are more vulnerable in the lower chamber where they are defending 41 seats without an incumbent on the ballot, the most since 1930.

In the Senate, which gives more voice to the rural voters who make up an important part of the Republican base, Democrats are defending 10 seats in states that Trump won in 2016, some by huge margins. That favours Republicans.

On the stump, Democrats have focused their closing messaging on defending the 2010 Affordable Care Act, popularly known as Obamacare, and its protection of insurance coverage for people with pre-existing conditions.

For his part, Mr Trump and the Republicans have focused attention on immigration issues, including a caravan of migrants from Central America headed through Mexico toward the US border. 

Yesterday, Mr Trump again took aim at migrants and sparked fury after tweeting a Republican campaign advert that has been described as one of the most racist political adverts in recent years. 

It shows footage of Mexican man Luis Bracamontes, an illegal immigrant twice previously deported, who in 2014 shot and killed two California police officers, and injured a third. 

In the video, Mr Bracamontes, who has been sentenced to death, is seen laughing in court and vowing to kill more officers. Words across the screen read: “Democrats let him into our country. Democrats let him stay.” It then shows migrants pulling on what appears to be a border fence.

Tom Perez, chairman of the Democratic National Committee, called it the “dog-whistle of all dog-whistles”.

“This has been Donald Trump’s playbook for so long, and when they go low, we go vote,” he told CNN. 

The advert, many say, recalls the notorious Willie Horton campaign ad financed by supporters of the George HW Bush campaign in the 1988 presidential election. 

That advert has since come to be seen as one of the most racially problematic in modern US political history since it played into white fear and African-American stereotypes.

It was regarded at the time as devastating to the presidential campaign of Democrat Michael Dukakis.

The controversy over the latest advert is yet another sign of the intensity with which the election campaign is being fought, bringing out the worst of Mr Trump’s combative instincts. 

That intensity appears also to be reflected in the mood of voters, as indicted in recent Reuters/Ipsos polling data.

The poll, which gathered emotional responses from more than 21,000 Americans over two months, found Democrats are most angry about the Trump administration’s now abandoned practice of separating undocumented immigrant families at the US-Mexican border, the potential for Russian interference in future American elections and the Republican president himself.

“It’s the most negative, blackest place to find yourself,” said Pattie Blair, 74, a Democratic voter in Phoenix, interviewed in the poll.

She says anger washes over her every time she sees Trump on television. 

“It’s like being in a bucket you can’t get yourself out of - a hand keeps pushing you back in every time you try to surface,” Ms Blair told pollsters.

Republicans meanwhile are most angry about the potential for Congress to try to remove Trump through impeachment, undocumented immigrants coming into the country and the mainstream news media.

The poll’s conclusion points to the fact that angry Americans will be more likely to vote, and Democrats are generally more angry about their hot-button issues than Republicans.

Another measure of the intensity in the election campaign so far is fundraising.

This year’s congressional campaigns were on track to break fundraising records for midterm elections, with Democrats having collectively out-fundraised Republicans. 

Senate Democrats raised at least $551 million, while Republicans raised at least $368 million. House Democratic candidates raised at least $680 million, while Republicans raised at least $540 million.

The total fundraising in each chamber topped what had been raised at the same point in the 2010 campaign cycle.

Despite polling data suggesting that Democratic candidates could get a turnout boost that exceeds expectations, possibly tipping the scale for them in tight races, observers are still urging caution over predicting the election result.  

That said, a “midterm wave” a sweeping electoral triumph that reshapes that national political map, is a recurring phenomenon in US politics.

“On the one hand, the pollsters could be underestimating the Democratic vote, particularly among young people and minorities, who tend to have low turnout rates in midterm elections,” observed New Yorker political journalist John Cassidy this week.

“If a powerful anti-Trump surge materialises in these groups, the much discussed “blue wave” could still drown the G.O.P. Conversely, the pollsters could be underestimating Donald Trump’s ability to turn out voters attracted to his divisive message, as they did in 2016,” added Mr Cassidy.

As the last few days have shown, the political gloves are now well and truly off in this midterm contest.

Tuesday will be an interesting day indeed and a telling one for the immediate political future of the United States. The fight for the soul of America is on.