MANAGUA, NICARAGUA, FEB. 2 -- President Daniel Ortega returned this morning from an eight-day diplomatic tour to Spain, Italy, Norway and Sweden that European diplomats here are calling relatively successful, both in financial and political terms.

The trip was viewed as an effort to discourage further U.S. support for the rebels, or contras, by highlighting European skepticism about the Reagan administration's pro-contra policy.

For the past 10 days the other eight members that with Ortega make up the top leadership of the ruling party have declined to be interviewed by the American press. The president's absence from Managua was described by diplomats and officials here as a related effort to limit comment that might provoke anti-Sandinista sentiment in the U.S. Congress as it approached Wednesday's vote on aid to the contras.

Sandinista officials have been particularly concerned to quell persistent reports of differences of opinion among them over a six-month-old regional peace process.

Ortega returned from Europe having secured pledges from the prime ministers of Spain, Italy, Sweden and Norway to help monitor the progress of the Central American peace accords.

Sweden reportedly promised $3 million in emergency drought aid and Norway considered helping Nicaragua with North Sea oil.

Few specifics emerged about what role the nations might play in observing a cease-fire, and several top officials noted that the approval of the other four Central American presidents, who joined Ortega in signing the Aug. 7 peace plan, would be necessary for the European participation.

The other Central American presidents have not commented on Ortega's trip. Diplomats here said it was decided here on the spur of the moment in mid-January, and that Ortega called Madrid, his first stop, to request an invitation. Spanish officials referred to his two-day stay there coolly as "a working visit."

Ortega did have his picture taken with King Juan Carlos and Queen Sofia before moving on to the Vatican for a significant meeting with Pope John Paul II. "For Ortega, a picture with the king and the pope is worth six hours behind closed doors with {Spanish Prime Minister} Felipe Gonzalez," said one West European envoy in Managua.

Today, Claude Cheysson of the European Community visited Managua to discuss the possibilities of increased European aid to Central America as a whole. He reiterated the community's "warm support" for the regional peace process.

These initiatives served to underscore the contrasts between what one diplomat called "Europe's emerging common approach" and the Reagan administration's support for the contras. "The idea is that, yes, you have a Marxist government, but it's a very peculiar one . . . and it will be here for some time," said one West European diplomat.

West European governments are concerned about what they see as the delicate position of Ortega himself, who they suggest is out on a limb with respect to more radical Marxists in his own party, as well as with the other, more mainstream Central American presidents.

"He could lose with both sides" if Congress votes substantial new contra aid, one European diplomat said. The Europeans fear that if the peace process collapses, as a result in part of Congress' decision, "you will get a really hard Marxist-Leninist Nicaragua forever and no solution at all," the diplomat said.