McLaren are currently leading the race in the constructors' standings, knocking Marko's team off the top spot at the Azerbaijan Grand Prix.
All eyes will be on the two papaya cars at the US GP weekend in Austin as they are expected to provide the fiercest competition to Verstappen's crown.
Have McLaren backed Norris too late?
Marko however, suggests they would be closer if they had managed their drivers better.
The 81-year-old consultant also claimed Verstappen will have what it takes to win a fourth consecutive drivers' championship.
McLaren have previously been coy as to who their primary driver is – with incidents such as the Hungarian GP, when the team let Piasrti overtake Norris, sparking numerous questions as to the best approach to battle Red Bull and Verstappen.
And Marko says that they've taken too long to get behind Norris as their main man.
He told oe24 :"We’re clearly seeing an upward trend with us. However, I must admit: recently, we’ve had the same problems as Ferrari and Mercedes: one moment it works, then it doesn’t, and we don’t know why that is.
"McLaren has been consistently quick. But it seems like they’ve waited too long to fully back Norris.
"That’s why he’s still far behind Max, although we’re hopeful that we can now give Max a car that he has more confidence in."