NEWARK, N.J. — Federal prosecutors and defense attorneys for Sharpe James will begin questioning potential jurors today in their effort to select 12 jurors and seven alternates to hear corruption charges against the former Newark mayor.

Mr. James, who as leader of New Jersey’s largest city for 20 years and a state senator for nine wielded enormous political influence, appeared subdued in court yesterday as he began the first of two federal corruption trials.

The usually talkative politician declined to comment on the case, saying little to reporters besides “good morning” as he entered the courthouse yesterday, just blocks from City Hall, his longtime base of power.

Mr. James, 72, is charged with five corruption counts, including conspiracy and fraud. His co-defendant, Tamika Riley, 38, faces those charges as well as eight others, including tax evasion. Both have pleaded not guilty.

Under federal sentencing guidelines, Mr. James could face seven to eight years in prison if he is convicted on all counts. But a judge could impose a much stiffer penalty — as much as 20 years on some individual counts.

Mr. James served as mayor of New Jersey’s largest city between 1986 and 2006 before deciding not to seek a sixth term. He also served as a state senator from 1999 to January 2008.

Prosecutors have said they expect the first trial to last as long as three months, with 40 to 50 witnesses expected.

Yesterday, U.S. District Judge William Martini spent nearly 30 minutes explaining the case to potential jurors, introducing the defendants and their attorneys and summarizing the pending charges. Attorneys reviewed responses from 131 prospective jurors who filled out questionnaires. They were asked to answer 38 questions submitted by prosecutors and defense attorneys.

The questions addressed issues ranging from newspaper reading habits and occupations to whether jurors believed they could judge the facts of the case without bias.

This morning, attorneys will begin questioning 67 potential jurors who responded that they could serve for the duration of the trial. If a jury is not selected then, another jury pool of more than 100 could be screened tomorrow. Trials held in the Newark federal court draw jurors from the northern New Jersey counties of Essex, Union, Bergen, Passaic, Middlesex, Hudson, Sussex and Morris. One of Mr. James’s lawyers, Thomas Ashley, said the defense hopes to seat jurors who can understand some of the complicated concepts of real estate transactions and the mayor’s relationship with the City Council, which the defense has maintained had the final say on land sales.

Mr. Ashley would not say if the former mayor would testify. Another of Mr. James’s lawyers, Alan Zegas, has said jury selection could take a week or two.

The first trial focuses on whether Mr. James, 72, abused his power in office by arranging for the sale of nine city-owned properties at discounted rates to Ms. Riley, a woman nearly half his age with whom he traveled.

Prosecutors said Mr. James improperly steered properties to Ms. Riley, and that with Mr. James’s help she quickly resold them at much higher prices. Ms. Riley was able to buy the properties although she lacked real estate, construction, and financial experience to rehabilitate them, according to the indictment. Prosecutors said they plan to present evidence that the mayor, who is married, had an intimate relationship with Ms. Riley.

Ms. Riley in March 2007 acknowledged the relationship in statements she made to federal agents before her arrest, according to court filings.

But she claimed that “it had not occurred to her” before the interview with federal agents that “her ability to get properties from James” was based on their intimate relationship.

In the second trial, Mr. James will face charges that he used city-issued credit cards for $58,000 in personal expenses while he was mayor, including trips with several women other than his wife to Martha’s Vineyard, Puerto Rico, the Dominican Republic, and Rio de Janeiro.