V8 Supercars CEO James Warburton says the category has done all it can to arm Team Penske with the information it needs to make a call on entering the championship.

Senior V8 Supercars staff have been in regular contact with the Roger Penske owned organisation since it first showed interest in the class late last year.

While it was hoped that a long-mooted tie-up with Dick Johnson Racing would have been locked away by mid-July, Penske president Tim Cindric has this week cast doubt on the likelihood of entering the championship at all in 2015.

“We’ve had every conversation we need to have and DJR have had as well,” Warburton told Speedcafe.com.

“There’s not really a lot more that we can do… it will really come down to a decision (from Penske) shortly.

“As administrators of the category we’ve got to make sure we express very clearly what the vision is, what the future is and what the expectations are around what we are achieving.

“I think we’ve been been very, very frank, open and honest about all of those things.

“They can now make a well informed decision.”

Penske’s extensive dialogue with V8 Supercars and DJR has occurred in parallel to its negotiations with potential sponsors and manufacturer partners in the United States.

Describing a 2015 entry as “difficult but not impossible”, Cindric has confirmed that Penske currently has none of the key deals it needs in place in order to commit.

Although Cindric’s visit to last year’s Sydney 500 came alongside that of Ford’s global motorsport manager Jamie Allison, a potential V8 Supercars tie-up between the parties failed to rouse the car maker’s interest.

“Right now we would have thought we would have been able to put together a program, but the facts are we don’t have one from a sponsorship side or manufacturer support,” Cindric told the V8 Supercars website.

“So I would say we are still doing our diligence and hoping we are able to put something together at some point.”

Another caught in the continued uncertainty over Penske’s V8 Supercars plans is Marcos Ambrose, whose future in NASCAR beyond 2014 remains unconfirmed.

Speedcafe.com understands that Ambrose has made preliminary moves to return to Australia next year, but may continue to race in the United States if a Penske V8 Supercars deal does not come off.

“If we have a picture develop there we would certainly like him to be part of it,” affirmed Cindric of Ambrose.

“But the driver perspective would be something that comes secondary to a lot of other things.”

Admitting that the current trying nature of the sponsorship market won’t have helped Penske’s V8 Supercars aspirations, Warburton stresses that the team’s interest is a positive reflection on the category.

“What I’ve learnt in international circles is the passion and respect from our product is extraordinary,” said Warburton.

“It’s a great feather in our cap so to speak that we’ve had a corporation of that credibility look this seriously at getting in.

“We’ll see what happens from here. It’s probably not the easiest time in life for these decisions, (because) sponsorship is hard generally.”

Penske’s famed IndyCar and NASCAR Sprint Cup teams are meanwhile currently in fine form in the United States.

Penske drivers Helio Castroneves and Will Power sit first and second in the IndyCar Series standings with four events remaining, while Brad Keselowski is third in the Sprint Cup having won two of the last three races.