NEW YORK (CNN/Money) - Arthur Andersen LLP vowed to fight back Friday as the accounting firm is the subject of a criminal indictment and several clients moved to drop Andersen as their auditor.

Chicago-based Andersen will plead not guilty to criminal obstruction of justice charges and plans to ask for a speedy trial to begin within the next 70 to 90 days, attorneys for the firm said.

"We want a trial right away but I can't predict what [the judge] will do," said Rusty Hardin, a Houston attorney for Andersen.

The Justice Department indicted Andersen Thursday for obstruction of justice related to the firm's shredding of Enron documents. In its indictment, Justice alleged that the accounting firm engaged in the wholesale destruction of documents, shredding literally "tons" of Enron Corp. documents, and purging volumes of information. On Oct. 23, Andersen began shredding documents even though it found out four days earlier about a Securities and Exchange Commission probe into Enron, the agency said.

Justice also claimed that the destruction was not limited to Andersen's Houston office but extended to offices in Portland, Ore., Chicago and London. Only on Nov. 8, when the SEC served Andersen with a subpoena, did the shredding stop, the indictment said.

However, the agency did not name or charge any individuals or Andersen partners in its indictment.

Andersen, Enron's auditor for 16 years, signed off on the energy trader's financial statements and later admitted to destroying Enron documents. Houston-based Enron, which filed the largest bankruptcy in United States history last December, allegedly used off-the-books partnerships to inflate profits and hide nearly $1 billion in debt. Enron fired Andersen as its auditor in January.

Andersen is considering many options in its legal defense. First, the firm will press for a speedy trial and may ask the judge to dismiss the indictment, said Stanley Brand, an attorney for Andersen in Washington. At the minimum, the firm will demand that the government produce the employees it believes were responsible and specify their actions, he said.

The firm is considering changing the venue, away from the much-publicized Houston locale but such a move isn't the top priority right now. "The principal thing is to get [the indictment] behind us as quickly as we can," Brand said.

Hardin insisted Friday that the indictment "is overkill" and could destroy the 89-year old Andersen, which was once the most powerful accounting firm in the world. Even if some Andersen employees are guilty of the allegations, it does not make sense to destroy the entire firm, he said. Andersen, the fourth largest global accounting firm, currently employs 85,000 employees.

"The collateral damage and consequences [of the indictment] are incredible," Hardin said. "How in world can you put a whole company at risk, and the jobs and the people? They are claiming we are Darth Vader."

Andersen has admitted from the beginning that the shredding of Enron documents did take place, Brand said. But Andersen has denied that senior management knew about the destruction and has attempted to lay the blame on fired Andersen partner David Duncan, who was in charge of the Enron engagement.

The government is now pursuing an indictment against Andersen and is apparently overlooking the fact that Enron executives plundered the energy trader for $800 million in stock options, Brand said. Enron Corp.'s former CEO Jeff Skilling testified twice before Congress that he did not know that Enron's various transactions were allegedly used to hide $1 billion in debt.

Kenneth Lay, another former Enron CEO, has refused to testify before Congress and invoked his Fifth Amendment right against self-incrimination. Both Lay and Skilling has so far escaped any indictments.

"[Andersen] is a soft touch now because one employee in Houston exercised incredibly bad judgment," Brand said.

Fallout from the indictment erupted quickly Friday when four Andersen clients dropped the firm as its auditor. Sara Lee Corp. (SLE: Research, Estimates), one of Andersen's 20 largest clients, switched firms as did Northeast Utilities (NU: Research, Estimates), Abbott Laboratories (ABT: Research, Estimates) and Brunswick Corp. (BC: Research, Estimates) The client defections are only the latest for Andersen as Freddie Mac, Delta Airlines and Merck, each longtime clients, all recently opted to choose other outside accountants.

A client exodus at Andersen is expected as proxy season -- when shareholders decide who will be their auditors -- has already begun. "Companies are meeting today to decide if they are going to keep Andersen," Art Bowman, of Bowman's Accounting Report, said.

Andersen said Friday it was "gratified that so many clients are staying" with the firm. But when asked if any companies had reiterated their committment to Andersen, a spokesman told CNNfn that he did not know of any.

The indictment is also expected to take its toil on Andersen personnel but as of Friday no partners or employees had resigned, the spokesman said.

The General Services Administration also suspended Andersen, Enron and several executives of both firms Friday from doing business with the federal government because of the accounting questions that led to Enron's collapse. The GSA also suspended David Duncan, the former chief Enron auditor at Andersen; former Enron Chairman and CEO Kenneth Lay; Jeffrey Skilling, another former Enron CEO; Andrew Fastow, Enron's former chief financial officer; and other executives and related firms.

If convicted of criminal obstruction charges, Andersen would face five years probation and a fine of $500,000. More importantly, if Andersen is convicted or pleads guilty it could not perform public audits, an SEC spokesman said.

The suspension would last until Andersen successfully appeals the rule or convinces the SEC that it is qualified to perform audits. The likelihood of Andersen winning in the last scenario is unknown.

"There is no precedent," the spokesman said.

Andersen can still conduct audits for now but must comply with certain conditions. Companies who are unable to be audited by Andersen, or choose not to be, may submit unaudited financial statements. But companies will generally be required to amend their filings within 60 days, the SEC said.

Andersen had been in talks this week with other members of the Big Five to sell or merge all or part of the firm. But as the threat of an indictment loomed closer, potential candidates dropped out of negotiations. Ernst & Young bowed out on Wednesday and Deloitte & Touche, considered Andersen's most likely merger partner, abandoned talks thereafter. PricewaterhouseCoopers, currently the world's largest accounting firm, said this week that it was not in merger talks with Andersen.

KPMG now appears as the only potential partner left. Merger negotiations between the two firms are still ongoing, different sources familiar with the discussions told CNN/Money. KPMG is believed to be interested in Andersen's European operations.

Sources told Lou Dobbs Moneyline Friday that the talks between KPMG and Andersen, expected to continue through the weekend, are far more substantive and promising than the talks that happened earlier this week with Ernst & Young and Deloitte.

Andersen's merger hopes are not dead, Bowman said. However, any combination would have to protect a potential partner from any liability or charges associated with Enron, he said.

"Any of the four would be willing to do [a merger] if they were shielded from liability," Bowman said.

Andersen on Thursday denied it would file for bankruptcy protection as a way to attract potential acquirers. Any talks of bankruptcy are premature and such an option has not been seriously considered, Brand, an Andersen attorney, said.

'You have to be insolvent [to file for bankruptcy] and we certainly aren't that," Brand said. "We are still a going concern. And we'd rather be a going concern."

But any possible combination would only be for Andersen's businesses in the United States. The European Union would likely oppose any firm merging with Andersen's operations in Europe, Bowman said.

"The only reason the FTC would allow [a merger] is because Andersen is in such dire straits," Bowman said.

KPMG declined comment.