The knives were out for Amy Klobuchar even before she stepped into a Minnesota snowstorm to announce her run for the White House.

In what looked like a pre-emptive strike, the Huffington Post published allegations that the Minnesota senator had mistreated her staff.

The bad publicity continued with the New York Times airing a surreal story of how Ms Klobuchar ate a salad with her comb and then ordered a staffer to clean it.

If little else, the hostile media salvo served to show that the battle to be Democratic presidential candidate in 2020 will be every bit as fractious as that which accompanied the fight for the 2016 Republican nomination.

The interesting question is why the knives have come out so swiftly.

One reason might be that she could be seen as the candidate who can straddle the gulf between the progressive and establishment wings of the party and as such, poses a threat to some of her more celebrated rivals.