Duarte visit reassures a skeptical Congress

El Salvador's President-elect, Jose Napoleon Duarte, shaking hands like a seasoned American lobbyist, won effusive praise from some of his most skeptical doubters during his rounds Tuesday on Capitol Hill.

Even opponents conceded that the goodwill visit will translate into more money with few strings attached for his Central American nation.

''You have to respect him,'' said Rep. Clarence D. Long, a sharp critic of United States policies in El Salvador. The Maryland Democrat, chairman of a House appropriations subcommittee, has played a key part in delaying $62 million in additional aid that is still hung up in Congress.

Although Representative Long proclaimed that ''I haven't agreed to anything, '' he gave a glowing report after Mr. Duarte paid him a personal call. ''He's courageous, intelligent, moderate,'' Mr. Long said. ''He's our kind of man.''

''He's talking our language,'' said Rep. Bill Alexander (D) of Arkansas, another administration critic on Central America, after the Salvadorean had breakfast with House members.

Even the foremost foe of increased military aid, House Speaker Thomas P. O'Neill Jr. (D) of Massachusetts, called the newly elected Salvadorean ''a very, very impressive man.''

''He thinks he's going to be in control'' of the military in El Salvador, said the Speaker, and with that argument, ''I think he has sold enough people in this House.''

The Speaker predicted the House would give more economic and military aid to that war-torn nation, although, he added, ''I still have grave doubts and am opposed to military aid in that section of the world,'' since he charged it would breed more violence.

The Duarte message in talks here was a plea for more aid to strengthen his position in El Salvador, especially among the military, which has long opposed him. While many in Congress favor requiring progress on controlling the right-wing death squads before giving aid, Mr. Duarte is seeking unrestricted aid.

Guarantees that Duarte would take full control of the armed forces of his country, that he would bring true democracy to his nation, and that he would take action against the political murders occurring in El Salvador convinced some members. ''I think most of us came away deeply impressed,'' said House majority leader Jim Wright (D) of Texas, a supporter of aid.

Another supporter, Rep. William S. Broomfield of Michigan, ranking Republican on the House Foreign Affairs Committee, said, ''I think a lot of minds, espeically of those who were critics, might have been reassured.''

But doubts still linger. ''To vote him any money now would be an act of faith ,'' said Long. ''We would have to assume that he would do what he says.''

At stake are two aid packages, one for $62 million in emergency military aid that has been pending in Congress since early this year and another proposal for

Although House resistance to the military emergency aid has tied up that bill , the Duarte visit could provide the boost needed to pass the bill this week.

But Long and others still point to a need for delaying the influx of dollars to the Duarte government. ''The argument against giving aid now is, we give him a stronger position with his own military,'' said Long. ''I'd like to get some proof that the military really is supporting'' changes such as progress on human rights.

Representative Alexander said, ''The question is how best to help'' Duarte. ''I would like to see conditions'' such as requiring prosecutions in political murders, numbered as high as 40,000 by the human rights group Amnesty International in a just-released study.

Restrictions on the aid would ''give the President (Duarte) an additional wedge to use against the large minority in his country that do not support him, '' said Alexander. ''He would be armed with an additional tool'' for forcing reform.

However, Alexander said that the House would probably go along with more aid with looser strings for Duarte.