"Overall I think we, together with Alonso, are the only ones who can consistently run at the front," Austrian Marko, Red Bull's motor racing consultant, told Servus TV.
He said McLaren's challenge has slipped away in recent races, even though "we can not ignore (Lewis) Hamilton".
"McLaren are having some problems at the moment, but it is a top team and Hamilton a top driver, and the points gap is quite small.
"Two or three good results and he is back up there again," added Marko.
British newspapers have decried McLaren's apparent slump, but former driver David Coulthard backed his old team to bounce back.
"They have the capability to win this championship," he wrote in the Telegraph.
"The rate of development in Formula One is astonishing," said Coulthard. "The introduction of a new package, small changes to setup, can make a big difference and it would not surprise me in the least if a McLaren won in Germany next week."