Sen. Ted Stevens’s criminal trial begins in earnest Thursday, after his defense team and government attorneys agreed to a diverse jury panel that could determine the fate of the Alaska Republican’s political career.

Each side will spend about one hour Thursday morning making opening arguments before the U.S. District Court for the District of Columbia. The Justice Department will then seek testimony from three former employees of the now-defunct Veco Corp. oil-services firm, including an engineer who designed an addition to Stevens’s chalet in Girdwood, Alaska.

The senator, who attended the jury-selection process on Tuesday and Wednesday, is pushing for a verdict in time to face reelection this November.

With his daughter in the audience, Stevens, 84, had no expression when the jury was selected Wednesday. But throughout the day, he appeared engaged, took notes and conferred with his attorneys from the Washington law firm Williams & Connolly. He returned to the Capitol later in the day and held a photo-op with fellow Appropriations Committee members.

The two sides agreed to seat 16 jurors, four of whom will serve as alternates. Eleven women and five men will serve on the panel, and most appear to be middle-aged. Nine women and three men are black, and also seated are two white women who appear to be in their 50s, one white man in his 20s and one Hispanic man who appears to be in his late 20s.

The jurors include a hospital clerk, an employee at Washington’s Newseum, an employee of a statistical analysis firm, a licensed paralegal, a sociology student, a woman with a background in economics, a receptionist, a third-grade teacher and a man who works at a drug rehabilitation and counseling center. Five have previous experience serving on a jury.

The heavily Democratic District likely produced a jury pool that has political leanings that tilt to the left. But Judge Emmet G. Sullivan instructed the jurors that those views must not interfere with their analysis of the facts of the case.

One white man, who appeared to be in his early 20s, was a member of the College Republicans in 2004 and hailed from a conservative Republican family. But he said he’s “become a more open person since college,” calling himself “very much middle-road” even though he saw Sen. Barack Obama (D-Ill.) speak recently in Baltimore.

One middle-aged black woman, a receptionist for a trade association, initially said she would give more weight to testimony by politicians and law-enforcement officers “because of the title and position the person holds.” But under instructions from the judge, she said she would give all witnesses equal treatment in evaluating their credibility.

Stevens’s team is trying to obtain medical records of the government’s star witness, Allen of Veco, to question whether a 2001 motorcycle accident in which he sustained head injuries has affected his memory. Stevens’s team is considering calling a cognitive neuroscientist in Texas to attempt to discredit Allen’s much-anticipated testimony, which has not yet been scheduled.

Stevens’s attorneys also claim that Allen is biased because, they argue, he cut a lucrative deal with the government in his sale of Veco to the firm CH2M Hill. The judge said Wednesday the defense could ask for records about the deal in order to determine whether Allen promised to give damaging testimony in exchange for Veco’s immunity from prosecution.

J. Taylor Rushing contributed to this article.