Former Nassau Chief Deputy County Executive Rob Walker pleaded guilty Wednesday to obstruction of justice.

Walker, who was once chief deputy to former County Executive Ed Mangano, was set to go to trial Monday in connection with receiving $5,000 in cash from a county contractor.

Last February, Walker was charged with accepting $5,000 and a free trip to a Notre Dame football game from a contractor who was seeking county contracts.

Judge Joan Azrack asked Walker on Wednesday if he was sure he wanted to enter a guilty plea in Central Islip federal court. Walker said, "Yes, I am, 100%." Walker then admitted that when he learned of a federal investigation into potential corruption in Nassau County government, including circumstances surrounding the $5,000 payment, he asked the contractor not to disclose the payment to the grand jury.

A second charge against Walker of lying to the FBI was dropped as part of a plea deal.

Walker was silent about why he decided to enter a guilty plea. His attorney said it was a fair resolution and that his client has accepted responsibility.

U.S. Attorney Richard Donoghue said in a statement: "While holding public office, Walker attempted to conceal his corrupt conduct by urging a witness to lie to the grand jury. Those who swear an oath to serve the public are expected to promote transparency, not obstruct justice."

Under sentencing guidelines, Walker will likely face 12-18 months in prison. The judge will make a determination after she receives a probation report.

A date for sentencing has not been set.