Red Bull team principal Christian Horner asserted after the Miami Grand Prix on Sunday that Sergio Perez's form is critical to helping the team take points away from Ferrari.
Perez came fourth despite being the only driver in the top 10 to pit twice and experiencing a sensor fault that resulted in a loss of power.
With that, Verstappen has only made an incremental gain in the driver's standings after his wins at Miami and Imola, with Leclerc now holding a 19-point advantage.
Horner believes Perez can join the fight and be on the podium but due to the car's reliability concerns was simply not able to do so in Miami.
"Of course, reliability's going to be an issue," Horner told Sky Sports. "We had a sensor issue on Checo's [Perez's] engine, the guys did well to move them around but he lost about 30 horsepower with that. He was losing half a second a lap and I think without that he might have even been second with the tyre advantage, because we pitted him.
"We need Checo in there and he's capable of doing that. You saw in Imola how quickly things can turn around and I think we've got some interesting races coming up.
"The car's running well, we've got some developments hopefully coming later in the summer that will help us, we need to save a little bit of weight, but generally, I think we're on a good trajectory."
With DNFs in Bahrain and Australia, Verstappen has fought off challenges from Leclerc to win the other three races of the season, showing distinct poise under pressure.
That was particularly the case in Miami, where the Dutch driver stayed consistent and managed to shake off Leclerc from the DRS window.
Horner was full of praise for Verstappen and how consistent he stayed despite the challenge from Ferrari.
"Max is under so much pressure in that position, it's easy to lock the wheel and so on, and he kept it clean," he said. "He didn't make any mistakes and then was gradually able to break the DRS after five-six laps and was able to manage it from there."