Gov. Jon S. Corzine on Monday underwent his third surgery on the left thigh bone he broke in a car accident last week that also left him unable to breathe without the help of a ventilator.

The operation at Cooper University Hospital, to clean out the six-inch wound, was "uneventful," said Andrew Poag, a spokesman for the governor. The surgery lasted about an hour.

Doctors said previously that they would evaluate after the surgery whether Corzine would be strong enough to breathe without the ventilator that was put in shortly after the accident on the Garden State Parkway on Thursday.

Corzine broke his leg and several bones in his chest Thursday night when the sport utility vehicle he was riding in crashed in Galloway Township, just north of Atlantic City. The SUV, being driven by a state trooper, was hit by another vehicle that swerved to avoid a pickup truck, sending the governor's vehicle into a guard rail.

Corzine, who apparently was not wearing a seat belt, had been on his way to a meeting at his mansion in Princeton between radio show host Don Imus and the Rutgers women's basketball team.

State Senate President Richard J. Codey has been acting governor since Thursday.

It was unclear how long it might be before Corzine can resume his official duties. His aides hoped that he would be well enough to govern later this week.

Doctors, however, say he'll face a long road to full recovery. Because he had a metal rod inserted into his leg, he probably will not be able to walk around normally for three to six months.

Doctors have also said that when Corzine leaves the hospital, he may have to go to a rehabilitation center before he can go home.

Corzine remained in critical but stable condition and was unable to talk because of the breathing tube.

Family members said he recognized them and responded to visitors when they saw him on Sunday.