By Roger Hardy
BBC Middle East analyst
The Bush administration is not hiding its frustration with Iraqi Prime Minister Nouri Maliki.
President Bush is unhappy with PM al-Maliki, but what are the alternatives?
President Bush is using blunter language than in the past.
"Will the [Maliki] government respond to the demands of the people?" he asked on Tuesday, during a visit to Canada.
If it does not, he added pointedly, the people will replace it.
Reinforcing the message, the US ambassador in Baghdad, Ryan Crocker, said the Baghdad government's efforts to promote national reconciliation had been "extremely disappointing".
US support, he warned, was "not a blank cheque".
Clearly stung, Mr Maliki has hit back, declaring he is the elected Iraqi prime minister and others should not interfere.
The comments of senior US officials do not go as far as those of Senator Carl Levin, a senior Democrat, who said this week that Mr Maliki had to go. But they indicate the administration's patience is wearing very thin.
The purpose of the current US strategy - the so-called "surge" launched in February - is to buy time for the Iraqi government to make political progress. It is a military means to a political end.
A report about the military "surge" in Iraq is due in September
But far from making progress, Mr Maliki's government is visibly falling apart. Virtually all of the Sunni ministers have either resigned or are boycotting cabinet meetings.
Its claim to be a government of national unity, never very convincing, is now threadbare.
Efforts to convene a crisis "summit" of leaders of the Iraqi political factions have so far come to nothing.
Many Sunnis have lost faith in a Shia-dominated government they regard as wholly unsympathetic to their needs. Some go further and see it as an Iranian-backed government deeply biased against the Sunni Arab minority.
The Iraqi rumour mill is, as usual, churning out a variety of conspiracy theories.
Some Sunnis suspect America and Iran will do a deal at their expense.
Adel Abdul Mahdi is a possible contender for the PM's job
Some Shia think neighbouring Sunni Arab states are ganging up to replace the Maliki government with one more to their liking.
But it is possible Mr Maliki will stagger on, albeit with his credibility diminished.
Parliament is in recess until early September. Some reports suggest the much-delayed "summit" will not take place before then.
That will be perilously close to the mid-September deadline when Ambassador Crocker and the top US general in Iraq, David Petraeus, are to appear before Congress to give their considered assessment of the "surge".
Two other names are regularly mentioned as possible replacements for Mr Maliki.
They are Adel Abdul Mahdi - of the Supreme Islamic Council of Iraq, one of the main Shia factions - and the former Prime Minister Iyad Allawi, who is a secular nationalist.
The first would be opposed by the Shia faction of Moqtada Sadr, a bitter rival of the Supreme Council. The second would be opposed by all the Shia Islamists.
In any case, it is far from clear that in current conditions any other Iraqi leader could do better. Changing horses is not a realistic US option.
Grumbling about Mr Maliki seems designed to step up the pressure on him rather than force him out.