WASHINGTON — Senator Stevens was clueless about the cost and scope of a pricey makeover of his Alaska cabin that led to federal corruption charges and threatened his lengthy career, his lawyer said yesterday at the opening of his trial.

Federal prosecutors allege that Mr. Stevens — one of Congress’s most powerful Republicans and a patriarch of Alaska politics for generations — lied on Senate forms about more than $250,000 in home renovations and gifts from a wealthy oil contractor and close friend, Bill Allen, who expected political favors in return.

But a defense attorney, Brendan Sullivan, in making the first public defense of the 84-year-old senator, shifted blame to Allen and responsibility to Mr. Stevens’s wife, Catherine.

“You cannot report what you don’t know,” Mr. Sullivan said. “You can’t fill out a form and say what’s been kept from you by the deviousness of someone like Bill Allen.”

Mr. Sullivan said the senator’s wife handled all the project’s finances and was the driving force behind the renovations. When Mr. Stevens had a message for her, he communicated through his Senate staffers.

“They have a saying in their house that when it comes to things in and around the teepee, the wife controls,” Mr. Sullivan said.

A longtime Senate powerhouse, Mr. Stevens has been highly successful in steering billions of federal dollars to his home state. But he now is such a political liability that the Republican vice presidential nominee and governor of Alaska, Sarah Palin, has not endorsed him in his unusually tight re-election race.

“Ted Stevens’s trial started a couple of days ago,” Ms. Palin said yesterday. “We’ll see where that goes.”

The Senate’s longest-serving Republican sat grim-faced at the defense table in a packed courtroom as a prosecutor, Brenda Morris, dismissed the theory that he was oblivious to what went on around him.

Ms. Morris portrayed Mr. Stevens as a crafty politician whose decades in office schooled him in the art of cultivating cronies and concealing gifts and favors.

“You do not survive politics in this town for that long without being very, very smart, very, very deliberate, very forceful and, at the same time, knowing how to fly under the radar,” Ms. Morris said in her opening statement.

At the heart of the case is a complicated 2000 home remodeling project in which Mr. Stevens’s small chalet in the woods outside Anchorage was jacked up on stilts and a new first-floor was built. Rather than hiring a home contractor, Mr. Stevens relied on Allen, the chairman of oil services firm VECO Corp., to manage the project, hire the carpenters, and review the bills.

Prosecutors say Mr. Stevens never paid Allen or VECO employees for their services, part of a long pattern of freebies he is accused of concealing. Allen gave Mr. Stevens a gas grill, a generator, an elaborate rope lighting system, and a sweetheart deal on a car.

“We reach for the yellow pages, he reached for VECO,” Ms. Morris said, “and the defendant never paid a dime.”

Mr. Sullivan countered that Mr. Stevens’s wife promptly paid every bill received — $160,00 in all — for the home project that was to make room for visits by his 11 grandchildren. He described Allen regularly going overboard with his giving, and at one point pressuring a local contractor to “eat” a $19,000 bill rather than send it to Mr. Stevens.

A potential witness in the case, Catherine Stevens, was not in court yesterday.

Allen has pleaded guilty to bribing Alaska lawmakers and is the government’s star witness against Mr. Stevens. He is expected to testify soon but was not due to take the stand Friday.