Steve Schmidt, who was chief strategist for the Republican's campaign during the 2008 election, said choosing Palin _ then a little-known Alaska governor _ helped the GOP gain ground against the Democrats and Barack Obama.
"I believe to this day that had she not been picked as a vice presidential candidate, we would have never been ahead, not for one second, not for one minute, not for one hour, not for one day," Schmidt said during a speech at the University of Arkansas Clinton School of Public Service.
"Her candidacy excited the Republican Party," he added. "There was huge excitement that transformed the race."
Earlier this month, Schmidt said Palin's presidential candidacy could be "catastrophic" for Republicans in 2012.
Schmidt declined to elaborate on his criticism of Palin and instead praised her Wednesday as someone with "great talents" in politics.
McCain said Sunday that Palin remained a formidable force in the Republican Party despite the criticism and that tensions are to be expected among campaign officials during and after a tough election.
Palin stepped down as Alaska governor in July and her memoir is coming out in November.