Former President George W. Bush will take the stage Monday evening alongside Jeb Bush for a highly anticipated rally in North Charleston, S.C., part of the Bush team’s effort to use the primary next Saturday in South Carolina — a state long favorable to the Bush family — to help reinvigorate Mr. Bush’s stalled presidential bid. The Bush campaign is also hoping the rally can seize on what was regarded as a strong debate performance on Saturday night…

“I’m proud of the fact he’s coming, and honored,” Jeb Bush, a former governor of Florida, told reporters on Thursday. “This is the first that he’s really kind of stepped out in the political realm since he was president.”

He added, “For him to come do this warms my heart.”

But the decision to deploy Mr. Bush’s older brother was a complicated one. The president led the nation into an unpopular war in Iraq, and Jeb Bush struggled early in his campaign to answer if he would have made the same decision, with the intelligence now available. There was also concern that George Bush, a more natural and charismatic politician, would upstage his brother, the more cerebral of the two, who can be awkward and gaffe-prone in person.