Porte was in commanding form despite being out-sprinted for the Stage 6 win by Astana’s Jakob Fuglsang.
More importantly, he was able to defend against Chris Froome (Sky) as they both put time into the likes of Alejandro Valverde (Movistar) and Alberto Contador (Trek-Segafredo).
“It’s nice to have the jersey but I know that the next two days are going to be super hard,” Porte said. “But, I feel up to it and we have the team here to try and finish it off on Sunday.
“I think I had the target on my back this morning but I have a fantastic team here. I feel good. I’m in good form and I would love to keep this jersey until Sunday.”
Overall, Porte (BMC) leads Froome by 39 seconds with Fuglsang in third place, 1min 15sec off the pace.
Valverde is fourth at 1min 20sec behind, after conceding 50 seconds, Fabio Aru (Astana) is at 1min 24, while Contador, who lost 1min 6sec on Stage 6, is now sixth overall at 1min 47sec.
The Tour de France's warm-up race reaches its climax on Stage 7 in the penultimate stage, a hard 167km effort featuring the ascent of the Col de Porte in the first 56km then to the steep 3.7km long finale on l’Alpe d'Huez via the 15.3km 6.9 percent Col de Sarenne.
The stage is likely to go to someone other than Froome or Porte with a number of pretenders hoping to escape.
Orica-Scott's Simon Yates and Dan Martin (Quick-Step Floors) may have a small window of opportunity for the stage win or more likely it will be a rider further down the general classification, like Lotto Soudal's Tony Gallopin.
Sunday's eighth and final stage is another mountain stage, with three big climbs and ending with an ascent of Plateau de Solaison.
Whoever comes out on top will be considered the frontrunner for the Tour de France, which begins on 1 July.