George Mitchell will be returning to the Middle East soon
The US has urged Israel and the Palestinians to press forward to re-launch deadlocked peace talks.
US Secretary of State Hillary Clinton is reported to have presented a downbeat report on US diplomacy in the region to US President Barack Obama.
Her comments come after a series of meetings between Middle East envoy George Mitchell and negotiators from both sides of the conflict.
Mr Mitchell is expected to travel back to the region soon, it was announced.
According to an anonymous official quoted by news agencies, Mrs Clinton is reported to have told the US president that "challenges remain" in US efforts to broker peace.
'Sense of urgency'
Speaking after the meeting, the official said the White House felt that "both sides need to move forward towards direct negotiations".
But in a speech on Thursday, Mr Mitchell said it was too soon to pronounce the administration's efforts in the Middle East a failure.
He said the president had "a sense of urgency, a sense of involvement and commitment" and said no other US administration had started working on the issue so early in their term.
The 76-year-old envoy, who will travel with Mrs Clinton to Morocco to consult Arab foreign ministers on the stalled peace process in early November, said he refused to be discouraged.
"We are determined to stay the course [...] until the job is done," he said.
Following the meeting, the White House said it recognised the efforts of the Palestinians in reforming institutions and improving security but said: "they need to do more in these areas and on stopping incitement and preventing terror".
The official also added that Israel, while having facilitated greater movement for Palestinians, needed to do more to improve their daily lives.
The Palestinians have said they will not take part in new peace talks unless Israel halts construction on occupied land in the West Bank.
But Israeli's Prime Minister Benjamin Netanyahu has rebuffed US demands for a total freeze on such building work.
Despite Mr Obama's attempts to make moving towards peace in the Middle East the centrepiece of his foreign policy, his administration has struggled to make progress on the issue.