Harris and Biden may take the headlines – but the Sanders and Warren clash is one to watch in second round of Democratic debates

It was the biggest moment in the first Democrat debates, California senator Kamala Harris taking former vice president Joe Biden to task over his political history on race. The type of moment that all of the other 2020 candidates on stage over the two nights would have hoped for.

The “rematch” between the two will be the headline event of the two new debates in Detroit on 30 and 31 July, with the media hoping that Harris strikes another blow, or Biden learns from his first performance and goes out on the attack. With Cory Booker – another candidate who has challenged Biden over his actions on race relations – also on stage for the second debate on Wednesday, there will no doubt be more questions for the former vice president.

Harris’s nationwide poll numbers have dipped from a peak just after her debate performance, from 15.2 per cent to 11.8 per cent, according to an aggregate of July polls by RealClearPolitics. Harris was polling at about 7 per cent before the debates, and will be hoping to make some gains second time around. As for Biden, he is at 29.3 per cent, from 26 per cent just after the debate and 32 per cent before it.

But rather than these sharp increases and drops, the first of the new debates on Tuesday may provide the more important clash for the long-term direction of the Democrat primary. Elizabeth Warren has made steady gains in the polls over the last couple of months and is now vying with Bernie Sanders for second place, polling on average 14.5 per cent in July to Sanders’ 15 per cent.

Both are trying to stake out their position on the left of the party – with Sanders following a similar line to his 2016 campaign and talking about a revolution. While Sanders has plenty of policies, the detailed and methodical nature of Warren’s plans – as well as having put out a large number of them – have been a hit with voters.

Warren was left virtually unscathed after the first debates, having appeared on the first night against a number of lower-polling rivals who seemed reticent to go after her. This time there is the difficulty of Sanders, particularly as both campaigns have largely stayed away from attacking each other given they share similar values.

Sanders has targeted Biden and Donald Trump more often, but he has been slowly shedding poll numbers as Warren has been gaining them.

This could lead to clashes, with both trying to be the voice of the left for the Democrats – but it will be tricky. Both camps need to find a way to distinguish themselves from the other to try to make some extra impact with the Democrat-voting public.

Pete Buttigieg – mayor of South Bend, Indiana – and former Texas congressman Beto O’Rourke are also on the first night, with Buttigieg having replaced O’Rourke as the fresh young, white male candidate in the race. O’Rourke, whose star was highest after the November 2018 midterms, is languishing in the polls and needs a big night. He will go after Buttigieg but may also decide he needs to target Warren, Sanders or both.

The first night of the debates has the disadvantage of only having less than 24 hours of coverage before being overtaken by the second night. Warren was remembered as having a good night in the first debate, but it was lost amid the Biden-Harris clash. Both Sanders and Warren will not want the same thing to happen, which is one of the many things that makes them being on the same stage so interesting.