The choice of Minnesota U.S. Attorney B. Todd Jones to head the Bureau of Alcohol, Tobacco and Firearms and Explosives (ATF) made him the face of a national anti-violence agenda growing from the shock of the schoolhouse shooting massacre in Connecticut.

But much like President Obama's effort to ban assault weapons and expand background checks on gun buyers, Jones' nomination has become stuck in the mire of congressional politics.

On Tuesday, nearly six months after his name was put forward, Jones is expected to face off with some of the most skeptical Republican critics of gun restrictions and the ATF, an agency that has become a stand-in for GOP ire with Obama's Justice Department and embattled Attorney General Eric Holder.

The White House has prepared Jones for a fractious grilling when he enters the Senate Judiciary Committee room. But the long-anticipated encounter also will give Jones his first chance to go on national television to answer questions that have been raised about his leadership as ATF's temporary acting director and Minnesota's top federal law enforcement officer.

"I am looking forward to meeting with the committee and answering all their questions," Jones told the Star Tribune.

To Iowa Sen. Chuck Grassley, the ranking Republican on the panel, Jones has a lot to answer for. Grassley has tried unsuccessfully to force Jones to testify about Fast and Furious, a troubled ATF gun-tracking operation on the Mexican border that Jones was brought in to clean up. Grassley also sought to tie Jones to a controversial Justice Department deal to drop two whistleblower cases against St. Paul as a means of averting a civil rights showdown before the Supreme Court over the city's rental code enforcement.

Grassley's numerous requests for documents are cited by Democrats as one reason for delaying the hearing.

The criticisms have become personal as well. Republicans have delved into anonymous complaints from lawyers in the Minneapolis U.S. attorney's office who accuse Jones of an overbearing "militaristic" management style that has fostered a "climate of fear." An internal ATF video warning of "consequences" for those who go outside of the chain of command was interpreted by some critics as a threat against potential whistleblowers.

Also "disturbing," Grassley said, was a letter from Donald Oswald, a former head of the Minneapolis FBI office, accusing Jones of "poor leadership" and an "atrocious professional reputation."

Against all this, more than two dozen law enforcement figures from around the country have provided character and professional references for Jones. Among them is Minnesota Bureau of Criminal Apprehension agent Michael Campion, Gov. Tim Pawlenty's public safety commissioner. In a letter to the committee, Campion quoted Pawlenty saying "law enforcement should be above politics."

Jones also received an endorsement from Minneapolis attorney Tom Heffelfinger, who was appointed U.S. Attorney by both Presidents George H.W. Bush and his son George W. Bush. Heffelfinger specifically rebutted Oswald's allegations, taking note of Oswald's brief tenure in Minneapolis: "One year in Minnesota is hardly long enough to learn how to shovel snow, much less long enough to learn what Mr. Jones' reputation is among local, state and federal law enforcement officials."

'Pawn in some larger fight'

Beyond Jones' qualifications for the job, the contours of the ATF nomination battle have long been established.

Since 2006, when the agency split off from the U.S. Treasury Department, the gun lobby has objected to every ATF nominee, including the choice of former President George W. Bush. In that sense, some analysts say Jones is as much a symbol as the active head of the ATF.

"To some extent, he does seem like a pawn in some larger fight," said Carl Tobias, a University of Richmond law professor who analyzes presidential appointments.

Nature of the beast

With a history or regulatory battles over guns and Second Amendment rights, the ATF long has been viewed with suspicion by the National Rifle Association (NRA) and other gun control opponents.

In the view of some analysts, efforts to deny the ATF a permanent director are a way to weaken the agency's regulatory mandate. "There's no question that a director nominated by the administration is going to get the full focus and wrath of anybody who has been upset about anything the ATF has done in the past," said Bill Earle, vice president of the ATF Association, which represents retired and current ATF employees. "It's just the nature of the beast."

While Democrats have the votes to approve Jones' nomination in committee, Republicans can still block or slow his appointment on the Senate floor. With the recent death of New Jersey Democrat Frank Lautenberg, Democrats might need as many as six Republican votes to overcome a potential GOP filibuster.

But on Tuesday, Jones will be buoyed by two familiar faces. Minnesota Democrats Amy Klobuchar and Al Franken serve on the Judiciary Committee, and have signaled their support for his nomination. Klobuchar, who has been assigned the gavel for the hearing, called Jones "well-equipped to lead the ATF."

Franken said he welcomes the "open, public debate" of Jones' record. Even if that's all he gets, it will be a step farther than the last two nominations, which never made it to public hearings.

"That," Earle said, "is progress."

Follow Kevin Diaz on Twitter at StribDiaz.