The Labour party seems to have inhabited three parallel worlds over the past fortnight.

There is a prime minister celebrating good news on the economy and lower migration figures and breezily insisting he will fight the next election, but with his party intent on deposing him.

There is a byelection where Andy Burnham, the party’s leftwing hope for prime minister, will have to demonstrate he can win over Reform UK voters on migration, and the bond markets on fiscal rules.

And there is the golden boy of the party’s right, Wes Streeting, unable to secure enough support to mount a challenge but merrily carrying on a campaign to win members’ hearts, with ideas including a decidedly leftwing plan for higher wealth taxes.

All of them are potential contenders in a leadership contest that does not exist yet. There is a chance it may not ever exist – depending on the whims of the voters of Makerfield, the ability of Keir Starmer to confront reality, Labour MPs’ appetite for risk.

But the fantasy contest has meant we are seeing surprising sides to its rivals. Burnham, who criticised the government as being too “in hock” to the bond markets, knows he must demonstrate economic credibility, especially if he wants a stable basis for his big plans on devolution and stronger public controls on utilities.

And he knows he cannot fight in Makerfield as “open-borders Burnham”, as his Reform UK opponents have called him – which is why questions on the EU and on easing Shabana Mahmood’s changes to the immigration system must be closed down quickly. But there is no doubt this will sting for progressive Labour voters who had hoped to see a bigger change of direction.

The stakes are without question higher for Burnham than for Streeting – and their audiences are completely different. For Streeting, there is a chance yet of a leadership contest and one in which, without a change of course, he may end up with a vote share like Liz Kendall’s 4.5% in the 2015 race.

As a consequence, he has over the past six months made his views far more explicit on key issues on the party’s left. He called for the recognition of a Palestinian state far sooner than his cabinet colleagues, and made a vigorous push in condemning Farage and far-right racism when the prime minister seemed criminally slow in doing so.

Now freed from the shackles of cabinet collective responsibility, Streeting has condemned the scapegoating of migrants and on Thursday issued the first detailed policy of his leadership campaign – a wealth tax centred on capital gains.

It would be unfair to say that either Burnham or Streeting is being inauthentic. Because they are both human beings and members of the same party, neither are actually what their public caricature suggests.

Burnham has been a business-friendly mayor of Manchester who has overseen the fastest economic growth in the country. He is not a bloodthirsty communist out to destroy the City of London, nor has he ever been a vocal supporter of more open borders.

Streeting has been a longtime campaigner against racism and the far-right, including on Gaza, and was one of the most vociferous anti-Brexit voices. These are not convenient Damascene conversions.

But Streeting’s left turn and Burnham’s right turn – to put it simplistically – are a symptom of the electoral bind that the Labour party finds itself in. Labour lost almost four times as many voters to the Greens than to Reform UK in the local elections, according to YouGov.

Those votes are piling up in cities with big Labour majorities that might go Green for the first time. And across the country, there are hundreds of seats with the tightest of margins that could fall to Reform with just a small number of switchers. No ambitious Labour leader – or prime minister – can afford to look in just one direction.