The pair were asked on a recent conference call if fans of the NBC a cappella competition could ever expect a collaboration between all four musicians in the future.
Bareilles replied: "I think there could be absolutely... We all really enjoy each other and respect each others' works so I think a collaboration would be a lot of fun."
Former 98 Degrees star Lachey added that he is a "huge fan" of Bareilles and credited Stockman's group Boyz II Men as being one of the reasons he became a singer.
"[Boyz II Men] were a complete inspiration and I've gotten to know Ben's work especially since getting to know him on the show," he continued. "As Sara said, I think that there's definitely a mutual respect for everyone and for their talents and it would be a lot of fun to see that happen at some point, to see a little collaboration."
However, Bareilles pointed out the "tricky part" of trying to organise any possible collaboration between the four would be trying to find time within everyone's busy schedules.
The Sing-Off's third season live finale airs Monday, November 28 at 8/7c on NBC, when either Pentatonix, Urban Method or the Dartmouth Aires will win the Sony Music recording contract and $200,000 prize.
Bareilles told reporters that the "energy will be sky-rocketing" during the finale, adding: "I'm thrilled to actually hand over the reigns to America to make the decision because I think it would be really tough to choose between these groups."
Voting is now open via phone, text or online at the official website.
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