Republican legislators have drawn a sharp bead on U.S. Attorney General Eric Holder, and by extension the White House, amid new revelations in the cross-border "gun walking" scandal.

U.S. Rep. Lamar Smith, R-Texas, on Tuesday called on the White House to appoint a special counsel to investigate Holder, who gave suspect testimony before Congress about Operation Fast and Furious.

The testimony in question was about when Holder learned about the botched gun-tracking operation in which about 2,000 firearms were allowed to be purchased by Mexican criminals, and how much he knew about it at the time.

Rep. Raul Labrador, R-Idaho, accused Holder of either lying to Congress or being incompetent and called for his resignation.

And U.S. Sen. John Cornyn, R-Texas, and a member of the Senate Judiciary Committee, wants Holder to return to Capitol Hill to clear up a discrepancy in his earlier testimony to the House.

"It's looking more and more like the typical Washington scenario where people get caught doing bad things but actually the coverup ends up being worse than the original offense," said Cornyn.

he rhetoric and accusations of coverup have become so heated, that even U.S. President Barack Obama jumped into the fray.

"He has indicated that he was not aware of what was happening in Fast and Furious, and certainly I was not, and I think that both he and I would have been very unhappy if somebody had suggested that guns were allowed to pass through (the border) that could have been prevented by the United States of America," Obama said in a news conference Thursday.

Neither the president's statement nor those issued by the Justice Department, however, are likely to dampen the controversy.

Operation Fast and Furious, a program initiated by the Bureau of Alcohol, Tobacco Firearms and Explosives, began in late 2009. The intention was to allow legal gun dealers near Arizona's border with Mexico sell firearms to straw buyers, who could be traced to Mexican drug cartels so as to build large criminal cases against Mexican crime organization figures.

But the ATF, which is under the control of the Justice Department, lost track of the weapons and traffickers. It is believed as many as 1,400 of an estimated 2,000 firearms purchased cannot be accounted for.

Weapons allowed to be purchased under the operation are said to have been used in criminal acts in Mexico. In December of last year, two of the weapons were found near the body of an ambushed U.S. federal agent.

An ATF agent then blew the whistle on the operation, which as a result was shut down. It was later revealed that rank-and-file agents were opposed to Fast and Furious but pressured by superiors to go along with it and that Border Patrol agents were ordered not to interdict the arms smugglers.

Congress began investigations; the acting head of the ATF was subsequently demoted and reassigned.

The fallout didn't end there. Holder, in testimony to Congress in May, said he had "probably" only learned of Fast and Furious "for the first time over the past few weeks." Heavily redacted Justice Department memos released this week indicate, however, that Holder was informed of the operation in July 2010.

That sparked allegations of misleading Congress in his testimony. Subsequent Justice Department explanations that Holder didn't understand the timing question and later suggestions that he may not have read the Fast and Furious memos stirred the pot.

The ATF, meanwhile, is continuing its house cleaning as a result of the scandal. B. Todd Jones, the new acting head of the bureau, announced Wednesday the reassigning of 11 top officials. Among them: Deputy Director William Hoover, who was demoted to special agent in the bureau's Washington office, and Assistant Director Mark Chait, who is being reassigned to Baltimore.