Palestinian leader Mahmoud Abbas has said he expects "very difficult times" for his people as he attempts to gain recognition for Palestine at the UN, BBC reported.
Mr Abbas was speaking on his way to New York, where he is to put the proposal to the UN Security Council on Friday.
Israel's deputy foreign minister said the move could increase tensions.
A BBC-GlobeScan poll suggests that in 19 countries across the world, more people back UN recognition of Palestine as an independent state than oppose it.
The Palestinians are seeking international recognition of their state based on 1967 borders - the West Bank, including East Jerusalem, and the Gaza Strip.
Israel and the US say a Palestinian state can only be achieved through direct negotiation, but the Palestinian leadership says this approach has got them nowhere.
The last round of peace talks between Israel and the Palestinians broke down a year ago.
"The Palestinian people and their leadership will pass through very difficult times after the Palestinian approach to the United Nations through the Security Council," AFP news agency quoted Mr Abbas as saying.
The Palestinian leader says his first step will be to ask for full membership at the Security Council, rather than going to the UN General Assembly to seek a more modest upgrade in status.
The US says it will use its veto to block the bid in the Security Council.
"From now until I give the speech, we have only one choice: going to the Security Council," Mr Abbas was quoted as saying on his way to New York.
"Afterwards, we will sit and decide."
He was also quoted as saying: "We decided to take this step and all hell has broken out against us."
Israeli deputy foreign minister Danny Ayalon said the Palestinians were "shirking their responsibilities first and foremost with their people".
"A unilateral declaration by the Palestinians of independence or any UN decision will actually be a vote for friction and conflict over co-operation and reconciliation and I think that would be deplorable for many years," he told the BBC World Service.
But he also said the upcoming vote was "not a serious vote because it doesn't matter."
"The joint assembly is more of a declaratory nature and carries no mandate," he added.
"The important vote is in the Security Council. There the vote will not pass."
In the BBC poll that surveyed global public opinion on the issue, 49% supported the proposal while 21% said their government should oppose it.
A total of 20,466 people in 19 countries were interviewed, either face-to-face or by telephone between 3 July and 29 August this year.
The margin of error ranged from + or - 2.1% to 3.5%.