WASHINGTON – A federal judge on Wednesday questioned what was behind the government’s decision to dramatically reduce the proposed size of a nationwide stop-smoking program, one of the penalties recommended in a racketeering suit against cigarette makers.

The government asked U.S. District Judge Gladys Kessler on Tuesday to require the companies to fund a five-year, $10 billion program, a fraction of the 25-year, $130 billion program suggested by government witness Michael C. Fiore, a University of Wisconsin medical professor.

The Justice Department called the $10 billion program an “initial request” that could be expanded.

But Kessler said Wednesday, “There may be some additional influences being brought to bear” on the government’s decision.

Democratic lawmakers sent letters on Wednesday to Glenn A. Fine, the Justice Department’s inspector general, asking him to look into what prompted the reduction in the request.

Associate Attorney General Robert McCallum said the government would address the stop-smoking program today, when closing arguments are set to end. He would not comment on what factors influenced the decision to seek a smaller program.

The Justice Department claims tobacco companies conspired to deceive the public about health risks of smoking. It filed suit under a civil racketeering law designed to prosecute mobsters.

As the companies began closing arguments Wednesday, they said the government has not proven its case and the companies have changed their business practices since the alleged conspiracy began five decades ago.

In February, an appeals court stripped the government of its biggest stick against the defendants by denying prosecutors’ request to seek $280 billion in allegedly ill-gotten gains. The companies contend the racketeering law under which the case was filed in 1999 limits what penalties Kessler can impose if she finds liability.

Among other penalties the government suggested were education campaigns and limits on discounts and in-store displays.

But the biggest price tag mentioned by the government’s witnesses on remedies was attached to the smoking cessation program.