Van Garderen entered the Tour with podium ambitions that are on track despite the American slipping from second to third overall after stage 14 on Saturday, and before the race hits the Alps.
The 26-year-old succeeded former team-mate Cadel Evans as BMC Tour top dog last year where for the first time he had the outright support of the outfit at the race.
Porte has outwardly stated his desire to step-up as a Grand Tour team leader and the reports that link the Australian with BMC prompt questions as to van Garderen’s future captaincy at the Tour, which general manager Jim Ochowicz has indicated is secure.
“He doesn’t have to prove himself,” Ochowicz said of van Garderen. “He did it last year, this year he is doing it better and I would suspect next year it will be even better again.
“He’s matured, he’s not over reacting to situations that happen every day and he’s leading the team. He’s moving people around in the race – they respect him for that – and with the pre-race strategy we put in place each day, he’s part of that decision making about how it’s going to happen and then he’s part of the decision making as the race matures each day.”
Under UCI rules, BMC and other teams cannot discuss rider transfers until August 1, although Porte did admit earlier in the Tour that he would be leaving Team Sky at the end of the year.
Ochowicz said BMC, who have won three stages and with Grand Depart winner Rohan Dennis marked a stint in the yellow jersey, have exceeded their race expectations, but one objective, with van Garderen, remains.
“We had set goals prior to getting here and we haven’t achieved them all yet because one of them doesn’t happen until Paris,” he said.
“We wanted to get the jersey one day, we wanted a stage win and we got the jersey and three stage wins so we’re two ahead right now but we’re still fighting for the podium.”
Porte’s departure from Sky could also make way for the British squad to blood another Grand Tour leader.
The 30-year-old has performed as a super domestique to 2013 Tour winner and current maillot jaune Chris Froome but has also had his own opportunities, this year notably at the Giro d’Italia where he abandoned a title bid on the second rest day following a series of set-backs.
Welshman Geraint Thomas has had a focus on the spring classics and smaller stage races in recent years but has shown, especially at this Tour where he currently sits sixth overall, the capacity to fill the spot.
“I will think about it next year,” Thomas said. “I’d love to do that one day but we’ll see how that goes.”
The peloton still has stage 16 on Monday, plus the Alps to conquer before arriving in Paris for the conclusion of the 102nd edition of the Tour, where planning for the 2016 race will commence.
Watch highlights from stage 15 of the Tour de France