In all fairness, Kamala is running a "blank slate" candidacy, but her record could well catch up with her.
No one really knows Walz either, but he has a record as Govenor that most people will not like if it ever comes out.
In the '88 election, Bush vs Dukakis, Bush made up a 16-point deficit against Dukakis in the last month to win.
Reagan was down 8-points against Carter the week before the election and won.
Trump vs Hillary.
Biden vs Trump.
Walz is a popular governor, but in an extremely progressive state. That helps in blue states, not some much in swing states.
The difficulty foe Trump is going to be getting enough of Harris & Walz' records and statements in the press left-wing press.