Former Senator Fred D. Thompson has yet to make a formal declaration that he is running for president, but already his noncampaign campaign has gone through its first shake-up.

A week of personnel turnover that extended from his campaign-manager-in-waiting down to volunteers raised questions about whether the Thompson camp is prepared to jump fully into the race for the Republican presidential nomination, a race in which his rivals have had months to establish their campaign organizations, raise money and hone strategy.

It also ignited speculation in Republican circles about who is really in charge, and in particular about the extent of the role being played by Mr. Thompson’s wife, Jeri Kehn Thompson, a former political operative.

On Tuesday, Tom Collamore, a top adviser to Mr. Thompson, stepped aside. At the same time, Mr. Thompson’s political operation announced that it was bringing in Randy Enwright, a veteran Republican strategist with ties to the Bush family, and former Energy Secretary Spencer Abraham, to take over the prospective campaign. The next day, the organization’s research director quit, and other staff members walked out.