When federal authorities began to investigate allegations of corruption involving prominent D.C. politicians and their campaigns last year, U.S. Attorney Ronald C. Machen Jr. took a keen interest in the probes.

Machen, the District’s top prosecutor, prodded his staff to work through weekends, demanded regular progress reports, set rigid deadlines and helped shape investigative tactics.

Although former and current prosecutors have described early friction in law enforcement circles over whether the probes would yield federal prosecutions, they said the effort paid off with recent high-profile guilty pleas and resignations.

“I’m not sure that without Ron’s leadership that the office would have gotten where it is on these cases,” said Thomas Hibarger, who resigned last month as Machen’s chief prosecutor in federal court to join a digital risk management company. “Ron really pushed us hard, rode us hard. . . . Ron is a force of nature.”

As if investigating D.C. public corruption wasn’t enough, Machen and his prosecutors were handed another difficult task June 8: spearheading a probe of leaks of classified material to reporters. That assignment came the same day that former D.C. Council chairman Kwame R. Brown (D) pleaded guilty to federal bank fraud charges; Brown resigned just days earlier when he was charged in federal court by prosecutors who, with FBI agents, began by investigating discrepancies in his 2008 council campaign.

Ronald C. Machen, the United States Attorney for the District of Columbia, speaks during a press conference outside the H. Carl Moultrie Courthouse of the District of Columbia. (Matt McClain/FOR THE WASHINGTON POST)

Brown’s conviction followed guilty pleas in which two top staff members on Democrat Vincent C. Gray’s successful 2010 mayoral campaign admitted to participating in an illegal scheme to improve their boss’s election chances. Federal prosecutors and FBI agents are investigating a prominent D.C. contractor — they seized millions of pages of records in raids — and his ties to city leaders.

High-profile job

That such cases landed in Machen’s lap is not unusual. As the District’s U.S. attorney, Machen has one of the most sought-after jobs in federal law enforcement.

The former partner at WilmerHale has labored to leave his own stamp on the country’s largest U.S. attorney’s office, which has about 300 lawyers handling matters in federal court and D.C. Superior Court and a budget that purportedly exceeds $70 million. (Although other U.S. attorneys have publicized their budgets, Machen has not.)

Machen, a tall and slightly bulky former college football player known for working so intensely that he has not yet removed Christmas decorations from his office, has left his mark in several ways — in public corruption convictions and by pushing prosecutors to get out into the community.

But his hard-charging style has alienated some, and he is battling an unusual number of departures by key supervisors and courtroom prosecutors, particularly those handling violent crimes.

Attention to detail

Unlike most of his predecessors, Machen relishes the minutiae of criminal prosecutions, including the trials of retired baseball star Roger Clemens — acquitted this week of lying to Congress about alleged steroid use — and of five men recently convicted of participating in shootings that claimed five lives in 2010.

His meetings run late because he and his top assistant, Vincent H. Cohen Jr., ask so many questions about investigative and trial tactics; prosecutors said it was not uncommon for a meeting that starts at 4 p.m. on a Friday to last well into the night. And he has been known to pop off e-mails with a question or an observation to line prosecutors at 2 a.m. — even about a minor offense.

“We sit in on meetings,” he said in describing his management style, in particular with bigger cases. “And we want updates with what is going on: What is the strategy? What is the investigative plan? We work very closely with our law enforcement partners. We don’t have the approach that it’s ‘hands off.’ We are also pretty aggressive in trying to work with the team to establish deadlines when we think things should be done and when things are done. And with that we had a lot of success.”

He added: “I have always been an ‘in-the-weeds’ guy — when I was a prosecutor and when I was at my law firm and where I am now. At the end of the day, it’s not ‘my way or the highway.’ It’s a collaborative approach: when we listen, when we talk. I think maybe there was some resistance early to that, because it is just something that is new. But I think people have really bought into it.”

The position is coveted by any number of politically active lawyers, and few U.S. attorneys stick around for a second term. Machen denied talk that he is expected to step down in September to give Cohen, his longtime friend, a chance to be acting U.S. attorney.

Downside of zeal

Machen’s zeal has drawbacks, according to current and former prosecutors. Numerous current and former staff members complained that his intensity wears down subordinates, that he meddles too much in cases and that he doesn’t seem to trust the supervisors who work for him.

Some complained that Machen runs the office like he was a partner at his old law firm, treating employees like associates and pushing them to work outrageous hours while he gets all the glory.

Machen said he sees himself as like a coach — a leader who sets the game plan, picks the players, and bears responsibility for wins and losses. His approach contrasts with that of Jeffrey A. Taylor, a recent U.S. attorney who said in an interview that he saw his role as helping teammates achieve their own successes. Numerous prosecutors have said Taylor was demanding but more trusting of his supervisors than Machen is.

Although overall attrition has held steady, Machen has lost at least a half-dozen experienced and respected supervisors. In recent weeks, at least six prosecutors have said they will leave the 35-lawyer homicide unit.

A federal hiring freeze has made it difficult to replace those prosecutors, and those remaining are beginning to complain of burnout.

Desire to achieve

Machen, a 43-year-old father of three, has close-cropped hair and an earring piercing in his left ear. He says he and his sister were instilled with a desire to achieve by their father, a chemist at Ford. Machen attended the elite Cranbrook School in Michigan, the same prep academy that graduated Republican presidential candidate Mitt Romney.

He played wide receiver as a walk-on at Stanford University. Upon graduation, he contemplated going on scholarship to the University of Michigan’s law school. But his father told him not to settle for the prestigious Big Ten university, and he went to Harvard instead.

Machen worked as a federal prosecutor in the District from 1997 to 2001, when he joined WilmerHale. He quickly became a partner.

An admirer of President Obama, he donated more than $4,000 to the Illinois Democrat’s various campaigns and worked as a volunteer on the 2008 campaign, helping to vet potential vice presidential candidates.

A spokesman for Machen said the prosecutor would not allow his respect for the president to affect his judgment as he helps lead an investigation into leaks of highly classified information that appeared in news stories.

Those articles highlighted the Obama administration’s active role in clandestine operations against al-Qaeda and other adversaries. Machen and Maryland’s U.S. attorney, Rod J. Rosenstein, were appointed to investigate the matter last week by Attorney General Eric H. Holder Jr. Holder was under pressure from congressional Republicans, who wanted an independent counsel to lead the investigations.

Staff writer Sari Horwitz contributed to this report.