"When will we make our driver announcement? I expect we will be making it quite shortly," team principal Martin Whitmarsh told reporters at the Abu Dhabi Grand Prix, with Button and Perez alongside.
Judging from the complimentary language directed at a relaxed-looking and smiling Perez, it would be a surprise if the Mexican was not retained after a difficult first season with the team following his move from Sauber.
The next race, the U.S. Grand Prix in Austin, Texas, is effectively a home race for Perez with it being the closest to Mexico in the absence of an appearance there.
"I think Sergio did a great race last week and that's the sort of thing that we love to see," said Whitmarsh after the Mexican built on his fifth place in India by out-qualifying Button in Abu Dhabi.
McLaren, the second most successful team in the sport in terms of wins and titles, have yet to finish on the podium this year and are staring at their worst season since 1980.
Button has finished in the top 10 in 12 races to Perez's eight and has scored nearly twice as many points.
"Both our guys are race drivers and they want to beat each other. We want that level of competition, that's how we run our team...the nice thing is we've got two really honest guys who like competing with one another," said Whitmarsh.
"I think they can do it cleanly and well and it stimulates all of us," added the principal, who was critical of Perez earlier in the season when clear overtures were made to Ferrari's Fernando Alonso despite the Spaniard's long-term contract with the Italian team.
McLaren are also seeking to bring Danish rookie Kevin Magnussen into the sport after he won the Formula Renault 3.5 series, with paddock speculation focusing chiefly on Force India and Marussia.
Whitmarsh said an announcement about the team's title sponsor, with the Vodafone partnership ending at the end of the season, would be made separately to the driver one.
"That will be beyond the end of the season because obviously we're respectful of the partnerships we have at the moment," he said.
"There's lots of deals done," added the Briton.