When campaign aides to former Maryland Republican governor Robert L. Ehrlich Jr. were indicted last month on charges that they sought to suppress black voter turnout last year, the allegations against Ehrlich’s right-hand man drew the biggest headlines.

But as the case moves to court Monday, the lesser-known defendant and his often controversial, behind-the-scenes work for Maryland political campaigns are poised to take center stage.

Julius Henson, an African American political consultant, has made a specialty out of getting people to the polls, most often black voters and most often for black Democratic candidates. Nearly an entire generation of local and state lawmakers in Prince George’s County and Baltimore owe at least one of their ballot-box successes — or failures — over the past 15 years to his no-holds-barred approach to campaigning.

Henson, 62, has called opposing candidates derogatory names, played on racial tensions and spread sordid details about opposing candidates’ lives. He once enlisted a group of blacks in Baltimore to shout down African American lawmakers as they endorsed a white candidate, Martin O’Malley, who was running for mayor.

And long before he worked for Ehrlich, Henson worked against him, labeling him in a previous campaign as “a Nazi.”

Although Henson’s brazen attacks often have worked, they seem to have backfired more than a few times.

Now, to avoid jail for Henson, he and his lawyers will likely have to convince a jury that recorded calls placed last November to many people in the predominantly black jurisdictions of Prince George’s and Baltimore did not cross the line into illegality. Henson and his attorney have maintained that the calls were an above-board attempt to aid his latest, and perhaps most unlikely, employer — a white Republican.

With the polls still open on Election Day, a woman’s recorded voice told tens of thousands of blacks who picked up the phone to “relax” and not to worry about going to vote because O’Malley (D), the incumbent governor, had already been “successful” in his rematch against Ehrlich.

Henson has hired a lawyer, Edward Smith Jr., who shares his client’s panache for the provocative. Smith said the calls were a far cry from notorious attempts to restrict the rights of blacks after the Civil War and before the civil rights movement of the 1960s.

“We’ve come an awful long way from the Black Codes and poll taxes, and we may have gone over the rainbow a little on this,” Smith said. “Political speech isn’t always moral, and it’s not always nice, but it’s political speech. There will be those who agree and those who will not agree, but I really can’t see what the big deal is.”

The case amounts to the second act in an embarrassing, three-part series of legal dramas for Maryland politics this year.

Former Prince George’s County Executive Jack B. Johnson and his wife have pleaded guilty to federal corruption charges stemming from more than $400,000 in alleged bribes. And state Sen. Ulysses Currie, a Prince George’s Democrat who was long one of the most powerful and popular figures in the General Assembly, awaits trial in September on charges that he took nearly $250,000 in bribes to arrange political favors for a grocery chain.

Of the three, many in Maryland political circles say, the most intriguing may be the case of Henson and Paul Schurick, Ehrlich’s de facto campaign manager, because of the broader verdict it may render on the state of race and politics in Maryland.

Henson and Schurick are scheduled to be arraigned Monday in Circuit Court in Baltimore. Each faces three counts of conspiracy to violate election laws, one count of influencing votes through fraud and one count of failing to identify the sponsor of the robo-calls. In addition, Schurick has been charged with one count of obstructing justice. All but one of the charges carry maximum prison sentences of five years.

Richard J. Cross III, who was Ehrlich’s press secretary and speechwriter, said he was puzzled by Ehrlich’s hiring of Henson and is troubled by what appears to have been a a series of attempts to manipulate the black vote over the past few election cycles.

Convictions in the case, said Cross, who was critical of Ehrlich during the campaign last year, could send a pointed message. “Hopefully, people will have a heightened sense of awareness and a diminished sense of tolerance for this kind of activity, which happens on both sides of the aisle.”

Maryland has a higher percentage of African Americans than any state outside the Deep South, and leaders of the state’s chapter of the NAACP and African American politicians have promised to use the robo-calls case to increase black voter turnout in the 2012 presidential race.

The case also could be the epitaph to Henson’s colorful career in Maryland.

Henson, who lives in Baltimore, burst onto the city’s political scene in the mid-1990s, leading Baltimore City Comptroller Joan Pratt (D) and Rep. Elijah E. Cummings (D) to surprising victories, partially with the help of early adoption of robo-calls. He then gave the city’s notoriously hard-nosed politics a new edge with his attack on O’Malley in 1999, which was seen as a setback for the candidate Henson was serving, Lawrence A. Bell III.

By 2002, Henson’s base had shifted toward Prince George’s, where his record in Baltimore and his close relationship with Rep. Albert R. Wynn (D) soon made him a mostly successful force in county politics.

One race he lost was that of M.H. Jim Estepp, the only white candidate to run in 2002 for Prince George’s county executive. “It was a mistake” to hire Henson, said Estepp, now the head of the Greater Prince George’s Business Roundtable. “I’m not going to elaborate — that period is gone, we’ve moved on in a different direction — but we knew almost immediately that it was a mistake.”

Henson maintained a winning record in the county until 2008, when Wynn lost to Rep. Donna F. Edwards (D). After that, Henson’s effectiveness waned. Of the more than $146,000 that candidates paid his Politics Today consulting firm last year, more than $132,000 came from candidates who lost, including more than $82,000 from Ehrlich’s campaign. Henson’s most successful win in Prince George’s was for Marilynn Bland (D), who won her bid for clerk of the Circuit Court.

“His strategy has always been to litter the streets with paper about his candidate. It’s a highly visible retail campaign, and then he hits the robo-calls and gets into the mean stuff. It’s slash and trash and slash, and I think it’s caught up with him,” said Del. Justin D. Ross (D-Prince George’s).

Henson consulted on Ross’s first successful campaign for the House of Delegates in 2002, but the two later had a falling out. “At some point Julius Henson’s techniques became so well known that he became part of the story,” Ross said. “By merely pointing out that your opponent had hired him, it was a strike against that candidate.”

Henson was in Georgia late last week , his attorney said, and unreachable for comment. Last fall, he took responsibility for the robo-calls but disputed that they were intended to suppress turnout among black voters. He said the call was “counterintuitive” and that it actually was meant to inspire Ehrlich supporters to vote rather than to keep O’Malley supporters home.

The Office of the Maryland State Prosecutor says it has recovered an elaborate plan Henson presented to the Ehrlich campaign for suppressing black votes. Lawyers for Henson and Schurick said the plan was rejected and not put into practice.

Wynn, who recalled that Henson always made his campaign’s “trains run on time,” said he was withholding judgement about the robo-calls case. “You have to see what the evidence proves. I’ve known Julius a long time. Let’s wait and see.”

Washington Post researcher Madonna Lebling contributed to this report.