The US Secretary of State, Mr Colin Powell, yesterday sent China a strong message that the US administration might not be able to contain the consequences of the current impasse unless the detained US surveillance crew being held on Hainan island is released soon.
But US officials over the weekend separately described President Bush as "hopeful" that the 21 men and three women would be home "soon and safely", and as "concerned and persistent" in urging China to release them.
Still reflecting a restrained approach, but insisting no apology would be forthcoming, Mr Powell joined other members of the administration on TV discussion programmes in arguing, in his words, that the delay could "affect the environment on Capitol Hill" in which decisions on a whole range of other China issues are made.
"The question of apology is something quite different," Mr Powell said, "because then we are being asked to accept responsibility.
"And that we have not done, can't do, and therefore won't apologise for that."
Although Congress is in recess for the week there is little doubt that if matters have not been resolved by the time it returns the White House may indeed lose control of the debate about future relations with China.
Reflecting the hardening of Congressional attitudes, the chairman of the House International Relations Committee, Mr Henry Hyde, over the weekend became the most senior politician yet to describe the prisoners as "hostages".
He too warned yesterday on CNN that issues such as arms sales, the Chinese Olympic campaign, and its World Trade Organisation accession could all be affected.
President Bush also faced a stinging attack from the right of his party. The Weekly Standard carried an editorial accusing him of displaying "weakness" and "fear" in "capitulating" to the Chinese.
Such weakness, it said, would be seen as a measure of Mr Bush's mettle.
Mr Powell said he had been receiving calls not only from Congress but from business people for whom the impasse was raising real questions about investment. But he also said that talks with the Chinese were "still on the road map described 24-36 hours ago . . . with occasional loggerheads, but I am confident we can get round barriers". The Vice-President, Mr Dick Cheney, also said the US had no plans to apologise. "The President has made it clear we regret the loss of the Chinese pilot as a result of this accident. The notion that we would apologise for being in international air space, for example, is not something we can accept," Mr Cheney said in an interview to be broadcast by NBC.
Meanwhile, China is still insisting the US should apologise and efforts to end the crisis could hinge on the choice of words in a letter that would allow a face-saving way out for both President Jiang Zemin of China and President Bush.
On Hainan island yesterday, the crew was given e-mails from home, toiletries and the latest American sports scores to boost their morale. The US defence attache, Brig-Gen Neal Sealock, said they were working hard for "unfettered" daily access to the crew. Free access to the 21 men and three women may buy time for what could be long and tortuous negotiations over the letter, which US officials said would also set out a mechanism for an exchange of views on the incident.