White House communications director Patrick J. Buchanan is testing his growing influence within the administration by pushing for a nationally televised presidential speech on Nicaragua that is opposed by other advisers to President Reagan, well-informed sources said yesterday.

Buchanan has urged the president to make a speech Sunday night, two days before a test vote in the House on Reagan's request for $14 million in aid to the rebel "contras" opposing the leftist Sandinista government of Nicaragua.

But the proposal has been opposed by deputy chief of staff Michael K. Deaver and political adviser Edward J. Rollins, both of whom are said to regard it as wasting Reagan's communicative talents in behalf of a request likely to be rejected. The issue remains unresolved.

Sources said that Buchanan first brought up the idea at a meeting shortly before Reagan left for Santa Barbara on April 5. Deaver immediately opposed it, saying that the president could accomplish more by lobbying members of Congress individually than by making a televised speech.

Others in the administration supported Deaver on tactical grounds because they preferred to have Reagan reserve television time for a speech on his embattled budget compromise, which comes up in the Senate next week.

"He can't win on the 'contras' and he can't afford to lose on the budget," said one senior official yesterday. "It's really a question of priorities."

The collision between the priorities of passing the budget and aiding the rebels posed an unusual challenge for an administration that during the first term usually succeeded in scheduling key congressional votes at times of its own choosing.

"Our essential rule was that you never scheduled two fights at the same time," said an official close to the administration.

In attempting to head off a televised speech on the Nicaraguan issue, officials said, Deaver received at least tacit support from a wide range of senior officials. Supporters of a budget speech reportedly included Rollins, national security affairs adviser Robert C. McFarlane and David A. Stockman, the budget director who with Senate Majority Leader Robert J. Dole (R-Kan.) is the architect of the pending budget compromise. Dole said yesterday he also has asked Reagan to make a budget speech.

When the Reagan entourage left for Santa Barbara, chief of staff Donald T. Regan reportedly told Buchanan and Deaver to work out their differences. But they never did. Deaver, returning to Washington after a brief trip to Santa Barbara, spent most of his time dealing with the controversy over Reagan's planned visit to a German military cemetery.

Buchanan stayed in Washington and directed preparation of a series of Reagan speeches on Nicaragua, starting with the emotional address the president gave Monday to a fundraising dinner for Nicaraguan refugees. That speech described Nicaragua as a "communist stronghold" seeking to "spread its poison through this free and increasingly democratic hemisphere."

High-level White House officials thought Deaver had prevailed regarding the speech issue, and reporters were told that the president would lobby individually for the contras. But Buchanan, who as a conservative columnist staunchly backed the rebel cause, continued to press for a televised speech.

Buchanan, with Regan's backing, gradually has been accumulating power in the White House and is expected to become the No. 2 man after May 15, when Deaver is leaving to open a public relations firm.

Staff chief Regan became the man in the middle after it was clear Buchanan and Deaver could not reconcile their differences.

"This has been a political test for Regan and he hasn't done all that well with it," said one official. "Buchanan keeps telling him that the problem is simply that our message isn't getting across. Don is a salesman and is inclined to believe him."

However, other officials said there was a practical case for Deaver's view.

"We are simply not going to win this vote next week," an official said yesterday. "The president should be saved for issues where he can do some good."