DuPont is said to be looking outside the company for a new chief executive to replace Ellen Kullman, who resigned with effect from Oct. 16.

The chemical giant’s directors reportedly have hired executive recruitment company Heidrick & Struggles International to find a successor. Recruiting inside the company could be difficult, due to personal loyalties, analysts have said.

Trian Fund Management, the hedge firm led by activist investor Nelson Peltz, which narrowly lost a proxy fight against the DuPont’s management earlier this year, is expected to want to influence the selection. The fund is now the chemical producer’s fifth largest shareholder.

At the top of the list of the mooted five leading candidates is DuPont’s interim chairman and CEO Ed Breen, 59, thought to be Trian’s pick. Breen, appointed to DuPont’s board of directors in February of this year, is also leading the search for Kullman's replacement. Breen is best known for presiding over the breakup of Tyco International.

Investors and analysts have picked four other potential new CEOs, according to a report by the news agency Bloomberg.

The list includes Jim Gallogly, who was publicly endorsed by Trian for a seat on the DuPont board of directors, but declined. Trian said it withdrew the offer after Gallogly insisted he get the CEO’s job, a claim the top manager denies. The 63-year-old led chemical producer LyondellBasell out of bankruptcy and prior to that ran Chevron Phillips Chemical for five years.

Dennis H. Reilley, 62, another analyst tip, was chief operating officer of DuPont before leaving in 2000 to become CEO of industrial gases producer Praxair. Currently chairman of Marathon and a director at Dow Chemical, Reilly became a Trian adviser in January of this year.

A fourth choice is Chuck Bunch, 67, chairman of PPG Industries, who served as that company’s CEO until September of this year.

At the end of the top-five list is said to be Joe Harlan, 56, currently vice chairman and chief commercial officer at DuPont competitor Dow and once considered to be in line for the top job at 3M.