WASHINGTON — The White House is threatening to revoke its invitation to Afghan President Hamid Karzai for a May summit with President Barack Obama amid an escalating feud triggered by lingering concerns in Washington over corruption in the Kabul government.

Robert Gibbs, Obama's press secretary, warned that the U.S. president may cancel a planned meeting with Karzai scheduled for May 12 in Washington following a string of anti-West comments that have shaken Obama's already-limited confidence in the Afghan leader.

"We certainly would evaluate whatever continued or further remarks President Karzai makes, as to whether that's constructive to have such a meeting," Gibbs told reporters.

"Our position on this is that when the Afghan leaders take steps to improve governance and root out corruption, then the president will say kind words. When leaders need to hear stern language from this administration about the consequences of not acting, we'll do that as well."

Relations between the White House and Karzai have deteriorated markedly since Obama made a surprise visit to Afghanistan on March 28.

During a tense private exchange, the U.S. president criticized Karzai for failing to follow through on promises to crack down on rampant corruption since his re-election in August balloting that was riddled with claims of voter fraud.

In public remarks during the same trip, James Jones, Obama's national security adviser, said Karzai needed to "understand that in his second term, there are certain things that have not been paid attention to, almost since Day 1."

Karzai responded during a speech last week in which he accused the West of trying to undermine his leadership and keep the Afghan government weak.

"They wanted to have a puppet government. They wanted a servant government," Karzai said.

The Afghan president then startled U.S. officials further by reportedly telling some Afghan parliamentarians last week that continued foreign meddling might prompt him to join the Taliban.

The remarks underscored the depth of mistrust between the Karzai government and the Obama administration just as the U.S. military surge in Afghanistan is nearing its peak, with the American troop presence to reach 100,000 this summer.

Gibbs pointedly refused to say whether the White House even considers Karzai an ally any longer.

"Karzai is the democratically elected leader of Afghanistan," Gibbs said in response to a reporter's question. "There are times in which the actions that he takes are constructive to governance. I would say that the remarks he's made (recently), I can't imagine that anybody in this country would find them anything other than troubling."

Karzai has not directly criticized the Obama administration in his recent complaints about foreign interference. Instead, he has targeted "foreigners" more broadly while denouncing, in particular, former United Nations officials who alleged fraud in last year's elections.

Karzai has accused Peter Galbraith, an American who served as the deputy head of the UN mission in Kabul, of being responsible for any fraud that occurred during the 2009 vote. Galbraith was fired last fall after accusing the UN of failing to properly track fraud that aided Karzai's re-election.

In addition to upsetting Washington, Karzai's recent anti-Western outbursts have thrown Canada's future role in the country into doubt, analysts say.

"These most recent troubling signs cast a shadow over Canada's engagement at a time when we are pondering our role in Afghanistan once the combat mission is over," said Elliot Tepper, senior research fellow at Carleton University's Centre for Security and Defence Studies. "Continuing (public) support for Canadian participation depends on . . . factors such as promotion of democracy and support for women, which will be drawn into question if our Afghan partner proves unreliable."

Karzai is bashing the West to capitalize on widespread Afghan mistrust of foreign intervention, said Mark Sedra, a senior fellow at the Centre for International Governance Innovation in Waterloo, Ont.

"There is a lot of anti-Western and anti-foreigner feeling in Afghanistan. The international community is a convenient scapegoat. By playing this card, Karzai can score some points with his own constituency," Sedra said.

Continued attacks by Karzai against the West could affect how Canada would respond to American requests for assistance in Afghanistan, Sedra said.

"When the United States does come calling with a direct request, or starts increasing pressure on Ottawa to perhaps contribute trainers or maintain some sort of commitment to Afghanistan over the medium to long term," Sedra said, "Canada will certainly have compelling arguments to say to the United States that we don't want to commit."

The focus by citizens of Western nations on the Afghan insurgency, election fraud and opium production obscures the political realities in the country, making it harder for Westerners to accept inflammatory rhetoric from Karzai, Tepper said.

"The Afghan-identity issue is central to this in a way that we tend to miss. The Afghan president is the leader of a fiercely independent state. They are extremely proud of never being conquered by anybody," Tepper said. "We almost have a structural problem in that he has to show that he is strong, fierce and proud and independent in order to be a true Afghan leader, and we need somebody who will say, 'Yes,'" Tepper said.

Gibbs dismissed Karzai's accusations of foreign vote-rigging.

"They're troubling. They're confusing. They've been investigated, and they've been found to be untruthful," he said.

"I don't know why somebody continues to insinuate that there was some sort of foreign corruption when the very thing that he speaks of was looked into. So I can't begin to decide what reasoning he had for making those comments."