Leclerc was the team’s clear frontrunner under Mattia Binotto, regularly eclipsing Carlos Sainz last season.
But Vasseur, who took over as team principal from a similar role at Alfa Romeo, is adamant the driver pair will start the new campaign with a clean slate.
He said: “The priority is to win for Ferrari. There will be no No1 and No2 but, if I need to take action at one stage of the season [to mark out a No1] I will do it. It doesn’t matter which one of them it is.
“It is a clear situation. We have two very good drivers and they are both able to do the job. We will have the capacity to provide them with exactly the same car, structure and support. The target is to win with Ferrari and for Ferrari.”
Binotto was replaced as team principal after another difficult season for the team in which they started as a pacesetters but quickly fell away amid a series of errors and lack of pace compared to rivals Red Bull.
But Binotto’s replacement in Vasseur believes Ferrari can recapture their glory days. He said: “We want to win and believe we can. After 32 years on the pit wall, I hope I can bring some racing spirit to the job.
“When you are a top team you cannot have another target than to win. You can’t start the season and say, ‘We want to finish second’. That shows a lack of ambition.
“We have everything to do a good job and the target is to win the championship. If you want to win the championship, you have to beat Red Bull. I am convinced we have everything to win.”