Will Yasser Arafat of the PLO do anything to support the new mainstream Arab search for peaceful resolution of Middle East conflict? He had an opportunity on the weekend when he met with King Hussein of Jordan in the wake of President Reagan's holdback on future F-16 warplanes scheduled for Israel.
Mr. Arafat could have responded to this US gesture for getting Israel out of Lebanon, as well as to Mr. Reagan's reported phone call telling the King he was prepared to be tough with Israel to obtain peace. The PLO leader could have offered full backing of Jordan as representative of the Palestinians under Mr. Reagan's peace plan.
''We must not lose this golden chance for peace in the Middle East,'' said Egypt's President Mubarak, urging the Palestinians to let Jordan represent them.
But, instead of seizing the moment, Mr. Arafat went on talking about having an Arab summit meeting. As of this writing, mainstream Arab peace advocates were left to note that, although Arafat belittles the Reagan plan (''trying to hide the sun with one finger''), he has not rejected it. They say the US still has time, though not unlimited, to demonstrate it has clout with Israel.
It is Washington's credibility as a negotiator with Israel that Hussein also wants demonstrated before entering into talks. Jordanian sources have said Washington could gain credibility by achieving a freeze on new Israeli settlements on the West Bank and an Israeli withdrawal from Lebanon.
Yes, as President Reagan often says, it takes two to tango. But now that Washington has started doing its stuff, Mr. Arafat risks being a permanent wallflower by failing to usher Jordan toward the dance floor.