WASHINGTON  Senator John McCain’s presidential campaign has gone through its second shake-up in a year. Responding to Republican concerns that his candidacy was faltering, Mr. McCain put a veteran of President Bush’s 2004 campaign in charge of day-to-day operations, and stepped away from a plan to have the campaign run by 11 regional managers, Mr. McCain’s aides said Wednesday.

The elevation of Steve Schmidt  who worked closely with Karl Rove  at Mr. McCain’s headquarters represented a sharp diminishment of the responsibilities of Rick Davis, who has been Mr. McCain’s campaign manager since the last shake-up nearly a year ago.

The shift was approved by Mr. McCain after several of his aides, including Mr. Schmidt, went to him about 10 days ago and warned him that he was in danger of losing the presidential election unless he revamped his campaign operation, two officials close to the campaign said.

The move of Mr. Schmidt is the latest sign of increasing influence of veterans of Mr. Rove’s shop in the McCain operation. Nicolle Wallace, communications director for Mr. Bush in the 2004 campaign (and in his White House), has joined the campaign as a senior adviser, and will travel with Mr. McCain every other week.