The race to unseat the speaker of the Assembly is heating up with the release of a mailer attacking Sheldon Silver for his handling of an allegation of rape against one of his top political aides.

The mailer was sent out yesterday to more than 35,000 residents in the Lower Manhattan district where Mr. Silver is facing a primary challenge from two political opponents. It includes a letter from Elizabeth Crothers, a former legislative aide who accused the speaker’s former chief counsel of raping her in 2001.

Ms. Crothers is supporting one of Mr. Silver’s opponents in the race, Paul Newell, and has taken an active role in the campaign by publicly criticizing Mr. Silver for his handling of the rape allegation — and accusing him of attempting to cover it up.

She writes in the mailer that when she went to the speaker for help after she was allegedly raped, he defended his former aide, Michael Boxley. Two years later, Mr. Boxley was indicted on charges that he raped a different legislative staffer, and he pleaded guilty to sexual misconduct.

“When I was powerless and alone, Sheldon Silver sat silent. His decision to protect a close political advisor had devastating consequences on more than one life. Like many politicians today who believe they are above the law, Sheldon Silver put his own political ambitions above justice. New York deserves better,” she wrote.

The mailer, which also includes snippets of news stories and editorials about Mr. Silver and his response to the rape accusation, was bankrolled by an Indianapolis-based organization, the Common Sense Coalition. It’s the first time the group has done any work in New York, the executive director of the coalition, Daniel Perrin, said.

A spokesman for Mr. Silver, Jonathan Rosen, said: “It’s sad that a shady, right-wing, out-of-state organization that refuses to disclose who its donors are is attempting to inject gutter politics into this campaign. It’s desperate and we are confident that Lower Manhattan voters will reject it.”

Mr. Perrin is a former executive director of the American Taxpayer Alliance, a group that received funding from energy companies and ran advertisements attacking Governor Davis of California for his handling of the state’s energy crisis in 2001. A Republican operative who ran Bob Dole’s presidential campaign, Scott Reed, also has run the group.

Mr. Perrin said he has no ties to Mr. Silver or the candidates seeking to unseat him. He said he read about Ms. Crothers in the newspaper and decided to help her tell her story.

“I know it’s incredulous that people actually do something about something they read that bothers them, but we are those people,” he said. He said he wanted every elected official in New York to learn a lesson from Ms. Crothers.

“If a young woman on your staff says another staff member raped her, you don’t just hold a press conference and say, ‘I have complete faith in my staffer.’ That’s not what you do,” he said.

A spokeswoman for Mr. Silver, Sisa Moyo, has said that the speaker has acknowledged that he was wrong about Mr. Boxley and has felt anguish over what Ms. Crothers went through.

A political consultant in New York City, Henry Sheinkopf, predicted that the mailer would have an impact on the race, but said Mr. Silver would not likely lose because of it.

“For some it will look like a last-minute piece of propaganda that has limited value. For others, it will be a decider,” he said, adding that, at the very least, it would probably increase turnout at the polls for the September 9 primary.

It is the first primary challenge Mr. Silver has faced in more than 20 years. His second challenger is an attorney, Luke Henry.

Mr. Newell outpaced Mr. Silver in fund raising during the latest filing period, August 5 to August 25, pulling in $40,015 for a total of nearly $37,730 on hand. Mr. Silver raised $19,575 in the last filing period, but has $2.94 million in his campaign war chest. Mr. Henry raised $510 and has $9,086 on hand.