Former House speaker J. Dennis Hastert. (Christian K. Lee/AP)

Former House speaker J. Dennis Hastert pleaded guilty in federal court here Wednesday to violating federal banking laws in a deal with prosecutors that allows him to avoid, at least for now, a thorough public reckoning of the sexual allegations that generated the case.

Hunched before a federal judge, Hastert spoke only when prompted and steered clear of specifics. He admitted that he withdrew money from banks in increments low enough to avoid mandatory reporting requirements and that he paid someone to keep decades-old misconduct a secret.

“I didn’t want them to know how I intended to spend the money,” Hastert said when asked to describe his misdeeds.

He did not address a more lurid allegation that the cash was meant to buy the silence of a former student he had molested years ago.

The plea marks a personal nadir for a man who served as House speaker for longer than any Republican in history. Friends and former colleagues said Wednesday that the case will undeniably tarnish Hastert’s reputation, and they were still trying to reconcile how the respected leader could have done what authorities allege.

“We’re all dismayed about the whole thing,” said Dallas Ingemunson, a former local GOP official in Illinois and longtime friend of Hastert’s.

Federal sentencing guidelines call for Hastert, 73, to face zero to six months in prison, although U.S. District Judge Thomas M. Durkin said Wednesday that he could deviate from that range. The maximum possible sentence for the charge is five years in prison. Experts said they expect Hastert to face only probation.

Hastert was charged in July with breaking federal banking laws and lying to investigators — ostensibly dull counts that prosecutors alleged stemmed from an intriguing plot. According to an indictment, Hastert, who was a teacher and wrestling coach in Yorkville, Ill., before he got into politics in the early 1980s, agreed to pay someone $3.5 million to cover up “past misconduct” against the person.

A federal law enforcement official has said the person was a former male student of Hastert’s who alleged that Hastert molested him years ago. The indictment says Hastert paid the person about $1.7 million from 2010 to 2014.

The molestation allegation never came up at Hastert's plea hearing Wednesday. Assistant U.S. Attorney Steven Block said Hastert paid a person who confronted him about past misconduct in an attempt to “compensate for and keep confidential” what he had done. Block said the misconduct had occurred decades ago and was “against” the person whom Hastert paid, but he did not name the person or say what the misconduct entailed.

Hastert acknowledged that after the bank asked about his large cash withdrawals — and he found out that they had to be reported — he started withdrawing smaller amounts to avoid scrutiny.

Former congressman Tom Davis (R-Va.), who worked with Hastert, said that although his friend and former colleague’s reputation might be sullied, he hopes his political legacy will not be. Hastert, who served as speaker from 1999 to 2006, brought the Republican Party together at a time when unity was sorely needed, Davis said.

“You may ban him from the hall of fame, but he was a great player,” he said.

Ingemunson said that he was happy the case was drawing near a close and that he still has “a hard time believing a lot of it.” Ingemunson, who said he had talked with Hastert since the indictment but not about the allegations, said he is particularly skeptical that Hastert sexually abused anyone.

“I don’t believe that,” Ingemunson said. “There’s no evidence of that. There’s no charges of that.”

Mostly reporters filled Durkin’s 14th-floor courtroom to watch Hastert’s plea, taking copious notes as he answered a series of mostly procedural questions. Hastert initially spoke softly — so much so that Durkin advised him to raise his voice — but he seemed to gain confidence as the hearing progressed.

Asked whether he is in good physical condition, Hastert joked, “Considering [I’m] 73 years old, yes.”

Although it is possible that more details about the case could be revealed at Hastert’s sentencing, scheduled for Feb. 29, experts said he was admitting wrongdoing probably in part to avoid an in-court airing of his past actions.

“I think that the detailed allegations that interest the public the most likely will never come to light,” said Jacob Frenkel, a white-collar criminal defense lawyer with the Shulman Rogers firm.

As a part of his written plea agreement, Hastert acknowledged that the U.S. attorney’s office at his sentencing would “fully apprise the District Court and the Probation Office of the nature, scope, and extent of defendant’s conduct regarding the charges against him, and related matters. The government will make known all matters in aggravation and mitigation relevant to sentencing.”

Block said prosecutors are still mulling over whether to call witnesses at the sentencing; defense attorneys said they would have none. The U.S. attorney’s office issued a statement after the plea, saying prosecutors would “provide the Court with relevant information about the defendant’s background and the charged offenses” at sentencing.

Hastert and his attorneys walked by a row of reporters without answering questions after the hearing.

David B. Smith, a white-collar criminal defense lawyer with the Smith & Zimmerman firm, said that though federal sentencing guidelines might call for a prison term, he doubted a judge would impose one.

“Unless the judge is just trying to punish him for the sexual offense that just couldn’t be prosecuted, I don’t see him getting any jail time, and I don’t think he should get any jail time,” Smith said.

Prosecutors’ view of the person Hastert paid remains unclear; he was referred to in documents and in court only as “Individual A.” Davis said he and others were curious to know more about him because the Hastert he knew did not seem capable of such egregious misconduct.

“I never saw anything in the speaker’s life when he was in Congress that was remotely contemptible or remotely at issue,” he said.