For roughly two decades, Ghazi Hamad has been a reliable champion for Hamas and its hard-line Islamist ideology, first as a leader of Palestinian street protests, then as an editor of a pro-Hamas newspaper and most recently as the chief spokesman for deposed Palestinian Authority Prime Minister Ismail Haniyeh.

Now, however, Hamad has emerged as one of Hamas' most caustic critics.

In an open letter to Hamas leaders, he criticizes the group as an uncompromising movement that's lost its way.

In seven blunt pages, he calls the group's military takeover of Gaza in June unjust and a "strategic mistake that has burdened the movement with more than it can bear." He accuses Hamas of being too stubborn to admit its mistakes. He chastises it for forgetting that militancy is a tool and not a goal. And he makes an emphatic appeal for Hamas to embrace "tolerance, pardon and reconciliation."

The reaction was somewhat predictable: Hamad, no longer Haniyeh's spokesman, was sidelined.

His letter exposed deep ideological fissures within the Hamas leadership, which appears uncertain how to deal with an Israeli economic campaign that's costing Hamas popular support and political options.

"Hamas has reached a crossroads where it really has to make a decision which way to go, and I think Hamas is deeply confused about what to do," said Basem Ezbidi, a political science professor at Bir Zeit University in the West Bank. "They basically found themselves cornered, isolated to a great extent and unable to articulate an acceptable, attractive alternative on the ground."

Mahmoud Zahar, a hard-line Hamas leader whose power appears to be rising, dismissed Hamad's views as the opinion of one man.

"The vast majority of people inside and outside Hamas are against his evaluation, and his statement doesn't represent the movement in general," Zahar said.

Hamad, who's reserved and contemplative in a movement that's characterized by fiery, strident leaders, declined to elaborate on his letter, which became public on a Web site operated by Hamas' secular rival, Fatah. But there's no doubt that his criticism reflects frustration with the ideological dominance of hard-liners and militants within the movement.

For years, Hamad, a voracious reader who recently has taken to carrying an Arabic copy of Richard Nixon's hawkish political treatise, "Victory Without War," has been among moderates who've sought to nudge Hamas from extremist militancy toward a more politically accommodating tone.

Last year, he encouraged Hamas to take part in landmark legislative elections that surprisingly propelled the movement into control of the Palestinian Authority. Caught off-guard by its own success, Hamas struggled to adjust when it took over in March 2006.

In his letter, Hamad criticized Hamas for squandering an opportunity to establish itself as a modern model for political Islam.

"Hamas lacks political guile and is facing politics with rigid positions and empty slogans," he wrote. "And many times it prefers to escape from politics toward the ideology of 'resistance is our strategic choice' in spite of the fact that resistance is a tool, not a strategy."

The letter wasn't his first public jab at Hamas. In the summer of 2006, two months after Hamas militants helped capture Israeli soldier Gilad Shalit from a post along the Gaza Strip border, Hamad warned in an opinion piece in a Palestinian newspaper that Palestinians "have lost our sense of direction" and descended into chaos and anarchy. The article, however, stopped short of blaming Hamas.

As street clashes between Hamas and Fatah grew worse, Hamad helped broker a deal to create a unity government, established last February, that halted the fighting temporarily. But the coalition government lasted only four months and ended with Hamas fighters routing Fatah forces in Gaza.

Since then, Israel and the United States have led an international campaign to isolate Gaza and support the pro-Western caretaker government created by Palestinian Authority President Mahmoud Abbas, Fatah's leader.

In the wake of the June military takeover, Hamas' once-solid popularity in Gaza has dropped off precipitously.

Hamas brought a semblance of security to Gaza, but soon ran into troubles when its police force violently broke up Fatah weddings, beat up Palestinian journalists and publicly accused Fatah leaders of being Israeli collaborators.

In early October, Hamad wrote an opinion column titled "This is the era of the wise men" in which he urged an end to the rivalry between Hamas leaders in Gaza and Fatah officials in the West Bank town of Ramallah.

"We have become baffled in our homeland, dispersed, fragmented and concerned for our future and fate," he wrote. "We have ended up under the sword of attrition, tension and a cold war between Gaza and Ramallah."

Even then, his criticism fell short of blaming Hamas.

Then came the open letter, which ended with an appeal for a new direction.

"I will stay true to this movement," Hamad wrote. "I will love it, but only under the umbrella of a broad nation, under the umbrella of an ideology that brings people together and doesn't divide and repel."