Beirut — Syria is moving behind the scenes to gain a more powerful role in Middle East negotiations. The result is not encouraging to peace prospects in the region.
Although international attention has been focused on the Palestine Liberation Organization and Jordan, the pro-Soviet regime of Syrian President Hafez Assad is also pivotal. It is set to play a spoiler role in both phases of peace talks now on the table - namely, the disengagement of all foreign forces in Lebanon and the overall Middle East plan announced by President Reagan Sept. 1.
President Assad has played the spoiler role before. During the first Arab League summit in Morocco a year ago, he did not show up at the last minute, and the conference held to debate Saudi Arabia's controversial peace plan had to be postponed.
There are fears Assad may attempt to do the same again with the two US-orchestrated phases of peace negotiations.
Being a front-line state is Syria's biggest asset. A poor, oil-less country, Syria has elicited billions of dollars in aid from Gulf states for armaments and development. It is supposed to receive $1.8 billion annually from Arab League pledges. The fragile minority regime would have little to give its people without this assistance. Its geographic position has also kept Syria in the political limelight internationally.
Syria appears to have three weapons:
* There are an estimated 30,000 Syrian troops in Lebanon's eastern Bekaa Valley, according to Western envoys in Damascus. Until Syrian, Palestinian, and Israeli forces withdraw from Lebanon, no significant movement can be made on broader peace.
* As host to the PLO's headquarters as well as the largest share of fighters, Syria is capable of wielding considerable influence over the resistance movement.
* The issue of the former Syrian territory of the Golan Heights, occupied by Israel since the 1967 war and annexed last year, offers sufficient grounds for Syria, with Arab support, to argue it should be included in the second phase, even though the Reagan plan does not officially mention the Golan Heights.
Although the Syrians have agreed in principle to withdraw from Lebanon, Assad has been making increasingly hardline noises over the past two weeks about the terms. In a speech marking the 12th anniversary of the ''corrective movement'' that brought him to power in a bloodless coup, he said the Israelis must pull back first. The US is attempting to negotiate simultaneous disengagement.
US special envoy Philip Habib has retuned to the region in part because of the bogged down negotiations on withdrawal, which the US had hoped would be completed by year's end. But three months after the PLO evacuated Beirut, there is as yet not a formula.
The delay may be in part related to the second phase of negotiations, because of the crucial element of timing. Ironically, Syria and Israel, which have publicly rejected the Reagan plan, share an interest in seeing the first phase slowed down so that the broader plan is also delayed.
As US officials in the region admit, the Reagan administration feels significant progress must be made on its peace initiative before the end of next year - the beginning of the 1984 presidential campaign. If the talks are not already under way the plan could become a hotly contested election issue.
Syria has not yet passed final judgment on the plan publicly. But in his speech, Assad was critical of ''proposals being suggested to the Arabs under the title of peace.'' And he blasted the US both for planning ''a total surrender of the Arabs to Israel,'' and demanding that the Arabs give maximum concessions before negotiations start.
Although Syrian officials have a long record of being more moderate than their public statements might indicate, Western envoys here say that, in this case, the Syrians would have to be offered major gains before even considering the plan.
''There is always a price tag with the Syrians,'' says one. ''And in this case it may be too high.''
The general consensus among diplomats is that the Assad regime would not alter its tune unless promised long-term US technological aid, massive Arab financial assistance, and the return of the Golan Heights.
Syria's position may also be influenced by the Soviet Union, which supplies most of the country's arms and warplanes. The Soviets have even more clout at the moment since Assad needs to replace more than 80 of the advanced fighters lost in dogfights with the Israelis over Lebanon, as well as destroyed tanks and artillery.
The Soviet Union is trying to push its own Mideast plan issued by former President Leonid Brezhnev. The Soviets are also aware that success of the US initiative would boost American prestige in the region.
On the positive side, diplomats contend that the Syrian record indicates the government does not like to play a spoiler's role unilaterally. ''They are not prepared to go down in history as being solely responsible for the failure of a plan everyone else accepted,'' says one European diplomat. ''Nor are they prepared to be isolated in the Arab world. They are too dependent on others for money.''
But in the tradition of manipulative Middle East politics, the Syrian regime does have a vehicle for issuing opposition to the plan: the pro-Syrian factions of the PLO.
Although chief Yasser Arafat is believed to want to see what King Hussein of Jordan might be able to get out of talks with the US, the majority of the eight factions under the PLO umbrella, now based in Damascus, have pressured him into placing conditions on acceptance of the Reagan plan: recognition of the PLO as the sole representative of the Palestinian people, and a fully independent state prior to federation with Jordan.
American officials have said in private that these demands are unrealistic.