A key witness testified on Wednesday that he was told Ted Stevens was “just covering his ass” in asking for bills to pay for extensive renovations that transformed the senator’s chalet in an Alaskan ski town.

Bill Allen, the former head of the now-defunct oil firm Veco Corp., testified in federal court that the Republican senator did not pay for major renovations, including revamped electrical wiring, a new power generator, expensive Christmas lights, new decks and stairways, a reworked rooftop and the addition of an entire ground-level floor that required his home to be lifted on stilts. The 71-year-old’s testimony is central to the gift-giving scandal that has landed the senator in criminal court.

In October 2002, Stevens sent a handwritten note to Allen asking him for a bill to pay for those renovations, citing strict Senate ethics rules on gift-giving.

“When I think of the many ways in which you make my life easier and more enjoyable, I lose count,” Stevens said in the thank-you note, which was admitted as evidence Wednesday.

“Friendship is one thing, compliance with ethics laws is different,” Stevens added.

In the note, Stevens said that a friend who was helping oversee the renovations, Bob Persons, a local restaurant owner near his home in Girdwood, Alaska, would remind Allen to give the senator a bill for the work.

In court on Wednesday, Allen said that Persons signaled that the senator only wanted cover by asking for a bill.

“Don’t worry about giving a bill, Ted’s just covering his ass,” Allen said Persons told him in 2002.

Sitting across the crowded courtroom, Stevens remained expressionless, and barely made eye contact with his former close friend of some 25 years.

Allen said he “really didn’t want” to send Stevens bills for Veco’s work “because I wanted to help Ted” and “because I like him.”

The government hopes the testimony will undercut one of Stevens’s main lines of defense: that the senator would have paid for all costs if Allen disclosed additional renovations he made when the senator was working 3,500 miles away on Capitol Hill.

Stevens has pleaded not guilty to charges of failing to publicly disclose more than $250,000 in gifts and home renovations from Allen and other longtime friends. His defense attorneys argue that he paid every bill he was given, including $160,000 in home renovations, disputing the government’s charge that the senator failed to pay an additional $188,000 tab.

Allen will continue testifying Thursday after Judge Emmet G. Sullivan scrapped the court’s Wednesday afternoon session because of an unspecified issue with a juror. Thursday’s testimony will include three phone calls the FBI tapped in which Allen was discussing the gifts he allegedly gave Stevens.