Hewlett-Packard Co. Friday launched its most scathing attack yet on dissident director Walter Hewlett and his opposition to the Compaq Computer merger, calling him a "man who has no plan" for the future of the company.

With less than a month until shareholders vote on the $21 billion merger and the outcome far from clear, HP board members said Hewlett's proposals announced this week amounted to a cobbled together, "now you see it, now you don't" strategy.

In the open letter to shareholders, HP said "You may have read that Walter Hewlett has a 'plan' for HP. Or perhaps you read that he does not have a plan. Maybe you read both, depending upon which day of the week it was, or what Walter Hewlett thought was expedient to say at the time ...

"So when Walter Hewlett tells you he has no plan and then says he really has one, and then vehemently denies he has a plan and then says he has a new plan -- all in a matter of two weeks -- only one thing is entirely clear: this is a man who has no plan for the future of your company or your investments in HP shares," the letter said.

Hewlett responded with a brief statement defending his calculations that HP would be worth $14 to $17 per share more without Compaq.

Hewlett said this week his alternative to the merger was a "focus and execute" strategy aimed at expanding HP's printing and high-end services division. However, he has been inconsistent in the terms he has used to describe that vision, telling Reuters he had a strategy, not a plan, then in a later statement referring to the "details of the plan."

"In its most recent letter to HP stockholders (the fourth this week), HP continues its unseemly campaign to attack me rather than attempt to support the merits, or lack thereof, of its proposed merger with Compaq," he said Friday.

Hewlett issued three releases on Tuesday alone and has been arguing against the merger in letters to shareholders and newspaper ads, while Hewlett-Packard management has launched an equally aggressive campaign of its own aimed at garnering support ahead of the March 19 shareholder vote on the Compaq merger.

Hewlett's ally, David Packard -- the two are sons of HP's legendary founders -- cast suspicion on HP's claims of strong support in the ranks on Wednesday, when he issued the results of a poll of HP employees in Corvallis, Oregon, in which nearly two-thirds opposed the deal.

A December HP survey of approximately the same employees had shown about three-quarters backed the deal.

In the Friday letter, HP board members lambasted Hewlett for waffling on whether he had a plan: "Your investment and your money are real -- Walter Hewlett's plan is not."

Hewlett has tried to keep the fight focused on whether to approve the merger, while management has argued that investors needed to be presented with a clear and preferable alternative in order to vote against the deal.

Both sides have taken to referring to the other in condescending terms, while calling for fewer personal attacks, in what has become something of a soap opera for the business press.

HP Chief Executive Carly Fiorina, who engineered the merger, has called Hewlett's opposition to the deal "irresponsible." For his part, Hewlett has made clear that if the deal is scrapped, Fiorina should be fired.