The departure of Pakistan's man in Washington, Ambassador Husain Haqqani, leaves U.S.-Pakistani relations temporarily adrift, with few trusted go-betweens after months of bruising political sparring that followed the Navy SEAL raid that killed Usama bin Laden.

Haqqani resigned Tuesday over what has become known as "memo-gate" -- allegations that he sought U.S. help to head off a possible Pakistani military coup after the bin Laden operation.

Former information minister Sherry Rehman, an important player in President Asif Zardari's ruling political party, was appointed Wednesday to replace Haqqani. With elections in Pakistan slated for March, however, Rehman will be diplomatically toothless if Zardari's government falls.

Haqqani's departure robs the two sides of a man who simultaneously was one of the Pakistani military's biggest critics and a constant, needling thorn in Washington's side, refusing American requests to expand the CIA's drone campaign against militants or increase American intelligence personnel on the ground.

When relations went south between the two sides, as they did after the SEALs killed bin Laden inside Pakistan, Haqqani, a former journalist with a prodigious Rolodex, kept lines of communication open with the White House, the CIA and the media by text, email and multiple daily tweets.

His history as a critic of the Pakistani military and intelligence services allowed him to act as a somewhat neutral go-between. He could smoothly shift from sympathetic listener to hard bargainer, as much counselor as diplomat, convincing the Americans he understood their frustration and assuring his Pakistani masters back home that he was standing firm against U.S. pressure.

Yet despite the fallout here, his departure is more about Pakistani political squabbles than U.S. relations, with Washington serving as foil to help the Pakistani military get rid of a longtime enemy, said Tim Hoyt, counterterrorism scholar at the Naval War College in Newport, R.I.

Haqqani's detailed account of the relationship between the Pakistani military and Islamic radicals in his 2005 book "Pakistan: Between Mosque and Military" was seen "as a grievous betrayal," Hoyt said.

The book won him accolades in Pakistani civilian circles and helped secure academic positions as a visiting scholar at the Carnegie Endowment for International Peace and an adjunct professor at Johns Hopkins University.

The ease with which Haqqani moved in such rarefied U.S. circles "helps explain why the military, the intelligence services and many elites in Pakistan view him as dangerously pro-American," Hoyt said.

But it also made him effective. When U.S. lawmakers threatened to withdraw aid to Pakistan, Haqqani was credited with changing their minds. When then-U.S. military chief Adm. Mike Mullen accused Pakistan of complicity with the Haqqani militant network in attacking the U.S. Embassy in Kabul over the summer, the envoy went into overdrive, working the phones and persuading U.S. officials to meet him at his office or at the Army Navy Club near the White House -- discreet conversations that helped keep some forms of military cooperation moving forward.

The former ambassador has no family connection to the Haqqani militant network.

"Removing him at this juncture in U.S.-Pakistan relations can only be viewed as a self-inflicted wound," Hoyt said.

The charges against Haqqani remain unproven. They rise from a leaked memo he says he did not write, delivered by a Pakistani American businessman, Mansoor Ijaz, who lives in London and has a history of making such claims with little follow-through. The Pakistani government says it will investigate.

The envoy and his supporters have claimed the memo was a hoax cooked up by the military establishment to get rid of Haqqani and weaken the Zardari government and democratic institutions -- explosive charges in a country that has seen at least three military coups.

Ijaz claimed he received the missive from Haqqani and, following his instructions, passed it to Mullen through an intermediary after the bin Laden raid. A spokesman said Mullen had received it but considered it unreliable and ignored it.

The memo accuses army chief Gen. Ashfaq Pervez Kayani of plotting to bring down the government in the political turmoil and finger-pointing after the raid. It asks Mullen for his "direct intervention" to prevent a coup.

In return, it promises help in installing a "new security team" in Islamabad that would be friendly to Washington.

Ijaz has led a high-profile media campaign attacking the ambassador. He claimed that Lt. Gen. Shuja Pasha, the head of Pakistan's main intelligence agency, flew to London to meet with him last month. Ijaz said he provided Pasha with computer records implicating Haqqani.

Ijaz has a history of making claims to be well connected with U.S. politicians. During the Clinton administration, he said U.S. officials told him Sudan was willing to turn over then-fugitive bin Laden -- claims the U.S. administration immediately denied.

Haqqani returned to Pakistan over the weekend to face questioning over the alleged memo by the army and the intelligence chiefs.

"I have resigned to bring closure to this meaningless controversy threatening our fledgling democracy," he said in a statement. "It was an artificial crisis over an insignificant memo written by a self-centered businessman."

"I have much to contribute to building a new Pakistan free of bigotry & intolerance," Haqqani tweeted after his resignation. "Will focus energies on that."

Christine Fair, a Pakistan scholar who teaches at Georgetown University, said she didn't expect Haqqani's departure to lead to a further downturn in U.S.-Pakistan ties, noting that both countries were continuing with cooperation on targeting al-Qaida and on drone strikes in the Afghan border area.

"So we're still getting from them what we need in terms of a bare minimum," said Fair. "It would be surprising if a new ambassador would try to sabotage that ... but you can't rule it out."