The door to the White House will some day open to the Palestine Liberation Organization, predicts a PLO leader.
Khalid Hassan, chairman of the foreign relations committee of the Palestine National Council, the PLO-dominated Palestinian parliament-in-exile, says the PLO favors mutual recognition and peaceful coexistence with Israel. But he adds that the PLO wants to know more about President Reagan's commitment to assuring Palestinian rights - meaning, in Mr. Hassan's view, some form of Palestinian statehood - before his organization can make further moves toward accommodation with Israel.
The PLO wants to know how serious Mr. Reagan is about pursuing his Middle East peace initiative and whether he can ''deliver'' on practical matters, such as his call for a freeze on new Israeli settlements on the occupied West Bank of the Jordan River. Israel has rejected a settlements freeze.
Hassan, one of the co-founders of al-Fatah, the dominant faction of the PLO, is considered one of the most influential PLO officials as well as a leading moderate within that multifaceted organization. Tall in stature but low-key in style, the moustached Hassan was in Washington when Reagan met recently with representatives from the Arab summit meeting at Fez, Morocco.
The PLO official was banned from entering the White House with the other Arabs, but he was consulted continuously by the others as they prepared for their talks with Reagan. The US has declined to recognize or negotiate with the PLO until it recognizes Israel's right to exist and renounces terrorism. Hassan had no trouble getting a visa to come here, however, because he is a citizen of Kuwait, traveling on a Kuwaiti passport.
Hassan's remarks indicate that the Reagan administration still has a long way to go before gaining Arab agreement to negotiations involving Israel. The administration wants Jordan's King Hussein to enter negotiations concerning the future of the West Bank and Gaza district. But Hassan makes it clear that the PLO would not at this point authorize Jordan to enter such negotiations. King Hussein has said that he cannot make such a move without an Arab consensus. The PLO, in effect, holds a veto. Other Arabs, says Hassan with confidence, ''cannot move one inch'' without PLO approval.
Hassan says the PLO favors the coexistence of two states - a Palestinian ''mini-state'' and Israel. But he adds that even if the PLO offered clearly to recognize Israel's right to exist, Israel wouldn't recognize the PLO.
''Even if we do this, the Israelis will not negotiate with us, and I think this is very clear to the administration, and mainly because of this, they are trying to push for King Hussein to negotiate,'' says Hassan.
''If we are up to the standard to authorize a King to talk on behalf of the Palestinian people, why are we not authorized to talk on our own behalf?'' he says. '' . . . What does Jordan know about what we have inside Israel, about our money, about our land, about our houses?''
''There is no need for anybody to negotiate for us,'' says Hassan. ''We are old enough to negotiate for ourselves. We are over 21.''
In announcing his peace initiative Sept. 1, Reagan opposed the idea of an independent Palestinian state, an idea that is anathema to the Israeli government. The US prefers a Palestinian confederation with Jordan. Hassan said that the PLO was for a confederation but only after the Palestinians had established a state of their own.
''As a people, we need a flag, we need a passport, and even, as one of our people said, we need the right to be arrested by a Palestinian policeman,'' says Hassan. ''This can be realized by what we call a ministate.''
Hassan says the Reagan proposal contains ''positive points.''
''When he said that the problem of the Palestinians is not a refugee problem, it's a national political problem, we are in agreement,'' the PLO official says. He adds that the PLO agreed with the ''five 'Nos' '' in Reagan's initiative: no to new settlements, no to annexation, no to occupation, no to the Israeli concept of ''self-rule,'' and no to Israeli control over all of Jerusalem.
''But the initiative did not include any clear 'Yesses' for the Palestinians, '' he says.
''I think the US should talk with us, . . . and if they find us reasonable, then a mechanism should be drafted as to what should be done, because whatever we say will be rejected by the other side,'' Hassan says.
''We have to continue moving,'' the PLO official says, ''and I think finally, we'll open the door . . . to the White House.''