Ron Johnson’s priorities were clear. “We have a huge problem with skyrocketing crime,” insisted the US senator for Wisconsin, accusing his debate opponent, Mandela Barnes, of pushing to reduce cash bail, release violent criminals and slash police funding.

Minutes later it was Barnes’s turn to go on the offensive. Johnson, the lieutenant governor said, had described the end of the constitutional right to abortion as a “victory” and shown himself to be “callous” and “out of touch”. Barnes promised to codify that right into law if elected.

A casual observer could have been forgiven for thinking the two candidates were fighting two different elections. For in split-screen America, Democrats and Republicans are largely talking past each other as they campaign for midterms that will decide control of Congress on 8 November.

Each party is playing to its perceived strengths. A recent poll by the political research firm Public Opinion Strategies for NBC News found that 90% of voters would prefer Republican control of Congress for the issue of immigration and the border, 65% favour Republicans on crime and 60% want Republicans to handle jobs and the economy.

The same survey showed that 86% of voters would prefer Democratic control of Congress to address climate change, 74% favor Democrats on guns, 71% prefer Democrats on abortion and 67% choose Democrats to cope with threats to democracy. The divide is unusually stark.

“In past campaigns, the top one or two issues in the election were closely contested and divided between the two political parties,” said Bill McInturff, a partner of Public Opinion Strategies. “This election is different. Each party holds a wide marginal advantage on a distinct set of issues.”

McInturff added: “America is more polarised than at any point in the last 40-plus years. Partisans have retreated to their own corners, with limited engagement between partisans, and very little to no overlap of agreement on any major issue.”

Perhaps the most vivid illustration of America’s divide is abortion. In June the supreme court’s rightwing majority overturned the landmark Roe v Wade ruling that had enshrined it as a constitutional right for nearly half a century. The political consequences could be profound.

The court’s decision prompted a surge among women registering to vote in some states. In conservative Kansas, people overwhelmingly voted to continue to protect abortion in the state constitution.

The upshot is a Democratic campaign intensely focused on mobilising women and young people around reproductive rights. Citing data from Bully Pulpit Interactive, the Axios website reported that Democrats have spent hundreds of thousands of dollars on Facebook ads about abortion over the past three months.

They were handed more ammunition when Lindsey Graham, a Republican senator for South Carolina, proposed a national abortion ban at 15 weeks, and when Herschel Walker, who supports an absolute national ban and is running for a Senate seat in Georgia, was reported to have encouraged and paid for an abortion in 2009 for a woman with whom he later fathered a child.

Just as Democrats are eager to talk about abortion rights, Republicans – who spent decades promoting it as a hot button topic – are now equally eager to avoid the topic. Candidates are waffling around it in debates and interviews, deleting hardline positions from their campaign websites and seeking to change the subject whenever they can.

But Democrats can take nothing for granted. Writing in the Guardian this week, Bernie Sanders, a senator for Vermont, said he was “alarmed” to hear that Democratic candidates are being advised that their closing arguments should focus only on the right to choose. “In my view, while the abortion issue must remain on the front burner, it would be political malpractice for Democrats to ignore the state of the economy and allow Republican lies and distortions to go unanswered,” Sanders wrote.

James Carville, a veteran Democratic strategist, also struck a note of caution, telling the Associated Press: “A lot of these consultants think if all we do is run abortion spots that will win for us. I don’t think so. It’s a good issue. But if you just sit there and they’re pummeling you on crime and pummeling you on the cost of living, you’ve got to be more aggressive than just yelling abortion every other word.”

Democrats have other cards to play: the climate crisis, gun safety and threats to democracy. While the last of these may be complex and abstract to some voters, former president Donald Trump’s continued scandals and campaign rallies are helping to keep it front and centre.

House Republicans, meanwhile, made their priorities clear with last month’s launch of a “Commitment to America” policy agenda, emphasising the economy, crime, freedom of choice and government accountability. They claim that Democratic rule has produced 40-year high inflation, 12 cities with record murder rates, a 60% increase in petrol prices, 3.5m illegal border crossings under Joe Biden and record-high drug overdoses.

Some of the attacks could be touching a nerve. Only 36% of Americans say they approve of Biden’s handling of the economy, according to a poll by the Associated Press-Norc Center for Public Affairs Research, while 63% disapprove. Although the president has blamed rising energy and food prices on Russia’s invasion of Ukraine in February, critics argue that his $1.9tn coronavirus relief package last year was excessive.

In a mirror of Republicans’s dissembling around abortion, Democrats are being forced on the defensive despite low unemployment. Biden told CNN this week: “I don’t think there will be a recession. If it is, it’ll be a very slight recession. That is, we’ll move down slightly.”

With Democrats similarly reluctant to discuss border security, Republicans believe that they hold the winning hand. Ed Rogers, a political consultant who worked in the Ronald Reagan and George H W Bush administrations, said: “Both parties are talking about what they can talk about. Republicans have the big four: inflation/economy; crime/lawlessness; public education, underreported in the US; the border/immigration.

“The Democrats have abortion and name-calling – you’re a fascist, you’re a Nazi, you’re an extremist. That’s all they have. I can’t believe how the Democrats have abandoned the big four. They just don’t talk about them. They’re in a swirl of denial, of obfuscation, of defeat.

“They just abandoned the ground. They’re not looking at the polling and selfishly saying, ‘Hey, gang, look at what people care about. We should have a well-crafted, affirmative message about these things.’ They didn’t have that meeting this cycle for some reason. It’s inexplicable to me.”

For voters, it can often seem like two campaigns running in parallel with little overlap. Instead of coming at the same issue from different sides, now the issues themselves are different. One team is playing baseball, the other cricket. Longtime political observers say it used not to be this way.

John Zogby, an author and pollster, said: “Usually there’s one set of issues. Pro, con, yay, nay. Not always but generally the economy. In the mid-90s crime was a big issue and there was no changing the subject. ‘Here’s our approach, here’s their approach.’ There was a common set of issues with different approaches. This is an election about different realities.”

He added: “We talked politics even when I was a little kid and there were always disagreements but what makes this so unique is, as [former White House counselor] Kellyanne Conway pointed out, there’s ‘alternative facts’ that are involved.”

The parties’ supporters do agree on one issue: last month a Quinnipiac University poll found that 69% of Democrats and 69% of Republicans say that democracy is “in danger of collapse”. But they have fundamentally divergent explanations: Democrats blame Trump and “ultra-Maga Republicans”, Republicans condemn Biden and socialism.

Biden ran for election as a moderate promising to heal divisions and he still peppers his speeches with an emphasis on the “United States of America”. But the past two years have seen continued acrimony and even talk of civil war as Trump continues to dominate an extremist Republican party.

Not everyone believes that the trend is irreversible, however. The Common Ground Committee, a non-partisan organisation, has launched a “score card” to assess the degree to which elected public officials and candidates for office seek points of agreement. Bruce Bond, co-founder and chief executive of the committee, argues that bipartisanship can actually be a selling point in the midterms.

He said via Zoom: “Because politics have become national and if I’m a Republican I’m going talk about inflation, and if I’m a Democrat I’m going to talk about the Dobbs decision [by the supreme court on abortion], there’s now a little bit more interest in saying, ‘I have this strong position on this issue and I agree with my base but I also can work with people from the other side’.”

Bond pointed to the example of Tim Ryan, a Democratic candidate for the Senate in Ohio, who has said he wants to represent “the exhausted majority” and work across the aisle. “What we’re seeing is that the candidates recognise that people are tired of the political divide. If you’re going to talk about the issues that you know your guys care about, that’s not going to be enough.”