Minnesota U.S. Attorney B. Todd Jones, President Obama's pick to head the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), came under scorching criticism Tuesday from Republican senators questioning his management style and his record on gun crimes.

"This is like a courtroom," Jones said midway through a 2½-hour hearing before the Senate Judiciary Committee, which could vote on his nomination in several weeks. "I feel like a defendant."

But as Republicans ramped up their attacks on Jones and Obama's Justice Department, Democrats on the panel praised the former Marine's composure under pressure. "I want to thank you for your very calm demeanor," New York Sen. Chuck Schumer said.

Virtually everything about Jones' testimony was contested, including the hearing itself.

Iowa Republican Chuck Grassley sought to postpone the long-awaited standoff pending a special investigation into allegations by Jeffrey Paulsen, an assistant U.S. attorney in Minneapolis, who says he was unfairly disciplined by Jones for raising management concerns.

"Mr. Jones' appearance today is no substitute for a full investigation," said Grassley, who also pressed Jones on an array of alleged ATF failures, including the controversial Fast and Furious gun-tracking operation that ended with the death of a border agent near the Mexican border.

It was left largely to Minnesota Democrat Amy Klobuchar, who presided over the hearing, to rebut GOP attacks on Jones' record. She pointed out that just as he took over the Minneapolis U.S. attorney's office shortly after the "turmoil" of staff dissension under Republican U.S. Attorney Rachel Paulose, he also was brought in as interim director of the ATF to deal with the aftermath of the Fast and Furious debacle.

"For the past two years, Todd Jones has been doing the impossible," Klobuchar said, "filling two crucial federal law enforcement positions."

Klobuchar suggested that some of the objections to Jones could arise from a desire to weaken the ATF, which has lacked a permanent director since 2006. "It seems that some members of the Senate don't want to [give] the ATF the benefit of a confirmed director," she said.

The agency frequently has been in the cross hairs of the National Rifle Association, and some Republicans on the committee took up the gun lobby's contention that even as Obama has pushed for new gun laws after the Newtown, Conn., school massacre, his administration has failed to enforce laws that are on the books.

One of the sharpest exchanges came with Texas Republican Ted Cruz, a rising Tea Party champion who sparred with Jones over data showing that of 48,321 attempts by felons to buy firearms illegally in 2010, only 44 were prosecuted by federal authorities — none in Minnesota.

"I would suggest the data demonstrate it is not a priority of the Obama Justice Department," Cruz said. "In my view, it's completely unacceptable."

"It's a small number," Jones conceded. But, he added, "the number doesn't tell the story about what the department has done" on higher priority cases involving armed career criminals, felons with guns and "straw" buyers who get guns for drug dealers and criminals.

Cruz questioned how Jones could call it a "major priority" to prosecute felons purchasing guns but then present no such cases in court.

Jones said limited prosecutorial resources must be focused on violent crimes and other high-profile cases. "I just want to make sure that's clear," Jones said, "so that my testimony is not twisted into something that it's not."

Then he added testily: "Your question, sir, was?"

Cruz shot back: "Are there any other so-called 'major priorities' on which you have presented zero cases?"

As Jones tried to emphasize the importance of violent crimes and white-collar cases with stiffer penalties, Cruz responded, "Mr. Jones, I would note you chose not to answer my question."

'An agency in distress'

Jumping to Jones' defense, Klobuchar noted that violent crime has dropped under Jones' tenure as U.S. attorney. She also pointed out that Texas' crime rate is twice that of Minnesota's. Cruz had walked out of the room by then.

The gun debate also came up with Minnesota Democrat Al Franken, who is also on the Judiciary panel. Franken asked if it would help to expand the system of background checks for firearms purchases, one of Obama's proposals after the Newtown shootings.

"I can tell you the current system is very effective," Jones said, "but there is always room for improvement."

Democrats have the votes to pass Jones through the committee, but it remains to be seen whether Grassley, the ranking Republican on the panel, will try to block the nomination on the Senate floor. Democrats would need six Republican votes to break a GOP filibuster.

In a possible effort to reach out to Republican moderates, Jones made much of his background as a lawyer in the Marines, his close-knit family and his deep roots in the Senate, where he once worked for Minnesota Democrat Hubert H. Humphrey, an icon of bipartisan comity.

Jones also offered up an unvarnished appraisal of low morale at the ATF, which he described as "an agency in distress" when he came on as interim director in September 2011.

Although Jones has been criticized for a "militaristic" management style in the U.S. attorney's office, Grassley faulted him for failing to exert enough discipline at ATF, where some of the key figures in the Fast and Furious scandal apparently escaped punishment through retirement and transfers.

Grassley expressed frustration at Jones' inability to discuss personnel issues at ATF in detail. But the Senate is likely to hear more about the Minnesota whistleblower case involving Paulsen, who according to Grassley has consented to open his case to the committee.

The U.S. Office of Special Counsel, which has been investigating the case, recently informed the Senate that because of insufficient evidence it has dismissed Paulsen's allegations of gross mismanagement and abuse of authority. Paulsen declined to comment for this story. His charge of retaliation has been referred for mediation.

Staff writer Paul McEnroe contributed to this report. Follow Kevin Diaz on Twitter at @StribDiaz.