Icahn has called leading shareholders in Nabisco Group Holdings but has not met with them or made his intentions clear, said a key Nabisco shareholder. "If Carl is serious, he'll start hitting the road and will speak to us pretty soon," said the source, requesting anonymity.

Icahn made two previous runs at the Nabisco board prior to the breakup in 1999 of the former RJR Nabisco's food and tobacco units and the creation of Nabisco Group Holdings. Icahn failed both times to dislodge the board. But this third tilt at Nabisco may be more serious, according to the leading shareholder and a leading M&A analyst.

The reason: death and taxes.

The last time Icahn challenged the Nabisco board, he urged the company to spin off its food division in defiance of possible legal action stemming from pending tobacco lawsuits. RJR Nabisco instead spun off its tobacco division, forming RJ Reynolds Tobacco Holdings. The remainder was stuffed into Nabisco Group Holdings, which holds an 80.1% stake in Nabisco Inc., the actual food unit.

Yet shares of Nabisco Group Holdings closed Wednesday at $9.38, up 8% on the day. Nabisco Inc., the actual food company, finished at $27.13, down 1% Investors fear that plaintiffs suing the tobacco industry will attach the assets of Nabisco Group Holdings after going through RJ Reynolds Tobacco. A court case in Florida threatens the tobacco industry with possible damages totaling as much as $300 billion.

How to overcome this legal threat? Mark Minichiello, a vice president at Spin-Off Adivsers, an independent Chicago research group, says Icahn must convince Nabisco Group Holdings shareholders that it is now time to rid themselves of the tobacco drag by finding a trade buyer rather than pushing for the spinoff of the food unit from its parent company.

And this is where taxes come into play. Last year's spinoff of Nabisco's tobacco unit was a tax-free event. To do it again, Minichiello says that Nabisco Inc. has to find a trade buyer. "You have to have an ongoing trade or business to avoid new taxes," he explains. "If they spin assets to shareholders, it would violate law 355," he said, referring to a section of the U.S. tax code that prevents the tax-free spinout of assets from a holding company with no other assets. "They do have several options to structure a sale in a tax-efficient manner," he added.

The sale to a trade buyer would also not jeopardize the tax-free spinoff of the tobacco unit in 1999, says Minichiello. "From what I can gather, the tax-free issue may not come into play. The IRS can see this was not planned prior to the spinout, so they may allow Nabisco to do it."

An adviser to Nabisco said he has come to a similar conclusion. If so, major food rivals might be interested in Icahn's sell-off gambit, among them France's Group Danone, Phillip Morris's Kraft subsidiary and PepsiCo, said bankers in the food industry.

Moreover, says Minichiello, a trade acquirer could protect itself from plaintiffs in pending tobacco lawsuits. "You'd basically have a couple of firewalls going up the ladder for protection," he explained, in the case of an acquisition.

One of Nabisco's leading shareholders cites another reason not to worry about the tobacco litigation. He expects the tobacco industry to appeal the Florida case, a move that will take several more years to reach its conclusion.

To him, fraudulent conveyance, the act of hiding assets from creditors, is not an issue. But that does not mean he is ready to vote for Icahn's slate. "Anyone that's paying attention is asking what can Carl do that the [Nabisco Group Holdings] board wouldn't do?" he asked. "I don't yet see how he drives value for me."