(CNN) Former President Barack Obama did something this weekend that he's been unable to do so far in the Democratic primary race: Call former Vice President Joe Biden and offer his congratulations.

While the two men speak regularly, the call from Obama on Saturday night came after Biden's victory in South Carolina. But the words of praise for Biden's commanding finish in the contest did not change the fact that Obama still plans to stay on the sidelines and not insert himself into the primary fight as it intensifies.

A person close to Obama told CNN that the former president's view has not changed: He has no immediate plans to offer an endorsement of Biden -- or anyone -- as the nominating contest heads into Super Tuesday.

"We are skeptical that an endorsement coming from us could truly change the political winds right now," the person close to Obama told CNN. If Obama were to endorse Biden, the person said, there is "a very real chance it backfires."

But more importantly, Obama still thinks his most valuable role is to try and unify the party.

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