The Carter administration's hope that the threat of military interference in the Dominican Republic presidential election had receeded was replaced yesterday by new fears of tampering with the electoral results in that Caribbean country.

Reliable sources said this renewed concern was prompted by reports that supporters of President Joaquin Balaguer are attempting to safeguard his reelection by allowing more than 150,000 pro-Balaguer voters, who had not been permitted to vote, to cast ballots.

The maneuver, the sources said, appears toi have backing from the Dominican armed forces, which want the conservative Balaguer retained in office. The military halted the vote-counting Wednesday after the returns showed Antonio Guzman, the left-of-center challenger, with 3-to-2 lead.

After the United States applied intense pressure, the armed forces appeared to the backing away and allowing the resumption of an honest vote count that most neutral observers believe would show Guzman the winner.

However, the sources said, reports from Santo Domingo yesterday indicated that the pendulum might be swinging back the other way - partly as the result of the military's anger over a public statement by President Carter on Friday.

Carter's statement, made after intense debate within the administration, warned that future U.S. support of the Dominican government would depend on an honest election, with the results honored by the armed forces.

Some State Department officials, the sources said, now think that the president's statement may have been counter-productive because the Dominican military commanders are fearful of charges that they backed down under U.S. pressure.

The sources said this concern caused the department to balk to having any of its officials testify at a hearing on the Dominican situation scheduled for today by a House International Relations subcommittee chaired by Rep. Donald M. Fraser (D. Minn.)

Sources on the subcommittee denied that the department refused to send witnesses. However, other sources said the administration showed such reluctance at talking about the Dominican situation in public that Fraser agreed not to press the issue at this time.

These sources said that represented a victory for Terence A. Todman, assistant secretary of state for Inter-American affairs. He originally opposed the Carter public statement and according to the sources, has continued to insist that any on-the-record comments by administration officials are likely to anger the Dominican military further.

The development most troubling administration officials at the moment, the sources said, has been the charge by Balaguer supporters that last week's balloting was fraudulent. They contend that thousands of Balaguer supporters, whose names did not appear on the official registration lists distributed to the polling places, were not allowed to vote.

Spurred by what appears to be the backing of the military, they now are demanding a subsidiary election that would permit these people to cast ballots, thereby swelling Balaguer's vote total to the point where he might emerge as the winner.