A Congressional fight over U.S. military training assistance to the government of Nicaraguan President Anastasio Somoza has further endangered the already tenuous position of the Carter administration's 1979 foreign aid request, according to informed sources.

The sources said the State Department fears that Somoza supporters in Congress, led by Rep. Charles Wilson (D-Tex.), will block the administration's international aid package, totaling approximately $8 billion, if a $150,000 training grant for the Nicaraguan National Guard is not included.

Wilson, a member of the House Appropriations Committee, has successfully held parts of the aid package hostage to the release of funds to the small Central American nation on at least two previous occasions this year. The funds, including a 12 million economic assistance program and $180,000 in supplies for a military hospital, had been withheld because of Somoza's muddled human rights record.

The reason those items were finally approved, one administration source said, was "in a word, Charlie Wilson."

Wilson, who describes himself as a "reasonable moderate." said in an interview that he has no interest in Nicaragua other than fighting both communism and liberals who, he said, skewed human rights policy in favor of leftist and strategically important governments at the expense of long-time conservative allies.

The administration source said Wilson has "caused a considerable amount of heartburn" in the State Department's Latin America Bureau through a near-constant barrage of telephone calls and personal visits on behalf of Nicaragua.

In many of these calls, Wilson threatened to press cuts in the portion of the foreign aid package that authorizes U.S. funds for contributions to international lending institutions and in aid for other countries, both Wilson and administration sources say.

Wilson suggested "that we release funds for Nicaragua, if we know what's good for us," the source said. "It's a question of one man shaping U.S. policy and becomes a question of the entire aid bill versus aid for Nicaragua."

As an example of his apparent power, the State Department credits Wilson, along with Somoza lobbyists, with successfully influencing the passage last year of $2.5 million in military grants and credits to Nicaragua. The aid was opposed by human rights advocates within the administration.

In its 1979 military aid requests, the Carter administration completely cut out Nicaragua, except for the National Guard training grant. State Department reports outlining repeated human rights violations by the 7,500-man National Guard provided the basis for the cuts. National Guard officers traditionally are not promoted until they receive U.S. training.

Although Wilson acknowledged pressuring for the release of previous funds earmarked for Nicaragua, he said that his most recent round of telephone calls to the State Department and liberal senators over the grant money "can in no way be interpreted . . . as an indication of an intention to withhold support for the foreign aid bill."

Still, said a State Department source, Wilson "has threatened the aid bill a million times before over Nicaragua, and that is in the back of all of our minds. He doesn't need to say it."

While Congress considers economic and military assistance as separate aid authorizations, it ultimately appropriates them as part of a single aid package. The House recently approved the military portion of the aid request, including the $150,000 for Nicaragua. The total aid package is due on the House floor next week.

Last May, however, the Senate Foreign Relations Committee dropped the training money from its version of the military aid authorization.

The authorization is to be debated on the Senate floor this week, and Wilson said Monday he "was told" that conservative Sen. Orrin Hatch (R-Utah) would introduce an amendment to reinstate the $150,000. Hatch's office confirmed that he is "toying with the idea."

Meanwhile, there appears to be a split on the issue within the State Department. Although the administration had included the $150,000 as part of its 1979 aid package, it did not protest when the Senate committee cut the funds. That ambivalence was reflected in an apparent decision early this week to leave unanswered a written request for policy clarification on the training funds from Sen. Richard Stone (D-Fla.).

The State Department has long been divided along the same lines as Congress. There are those who believe Nicaragua's human rights problem is not as bad as other countries receiving U.S. military assistance such as Iran and the Phillipines, and those who would like to end the long and newly embarrassing U.S. support for the unpopular, dictatorial Somoza government.