Richard Hackborn - a 33-year HP veteran who has held various high-level executive positions at HP, including the company's chairmanship - is a strong supporter of the planned merger. He resigned from the Hewlett Foundation after six years on its board in protest at the Foundation's intention to vote against HP's proposed acquisition of Compaq.
"Their opposition does not address any of the issues or opportunities of this company," Hackborn said in a statement. "Our plan secures HP's future."
The Hewlett Foundation is led by Walter Hewlett, son of HP co-founder William Hewlett and one of the most active opponents of the merger. William Hewlett confirmed his intent to wage a proxy battle against the deal last week, following a decision by the David and Lucile Packard Foundation to oppose the merger.
"Walter Hewlett's decision to wage an ill-advised proxy fight opposing HP's merger with Compaq deeply conflicts with my and the HP board's belief that the merger represents the very best way to deliver the value and growth [that] HP's shareowners, customers and employees deserve," Hackborn said in a statement.
Hackborn and other HP executives, including HP's chief executive Carly Fiorina, have pledged to forge ahead with the merger despite opposition from members of the Hewlett and Packard families, who together own about 18% of HP's shares.
On 12 December, the executive in charge of integrating the operations of the two computing giants held a press conference to tell shareholders that the company's board had no intention of calling off the merger. The company again responded to opposition in a statement released on 13 December.
"The majority of HP employees are in support of the merger, as per our survey data, and we are not seeing negative impact to our customer relationships because of the merger," HP said, opposing Hewlett's proxy-fight intentions.
Hackborn's decision to quit the Hewlett Foundation's board could hurt the proposed merger because it widens the rift between supporters and opponents of the deal, said Rob Enderle, an analyst with Giga Information Group. It could also make it more difficult for HP to win support for the merger from shareholders, who are pegged to vote on the merger plan within the next three months, he said.
"They need to turn around these foundations," Enderle said. "Resigning from the Foundation doesn't build anybody's confidence. This is just one more bad political move."
The merger was valued at around $25bn (£17bn) when it was announced in early September.
Hackborn said in a New York Times article this week that he has been one of the pillars behind HP's efforts to acquire Compaq. He told the Times that if shareholders don't approve the merger, the board and top management would probably walk away from the company. "They will have to get a board and a management to fix the PC business and these other problems."