President Bush Friday unveiled a bipartisan Contra aid plan as the first plank of his emerging foreign policy, outlining a $4.5-million-per-month program that commits his administration to support Central American peace efforts.

The agreement for the first time offers money to the Nicaraguan rebels that can be used to resettle in their homeland and rejoin political life there."Does it mean an end to the war? Let's hope so," said Secretary of State James A. Baker III, a chief architect of the accord. Bush said, "The burden of proof is on the Sandinista government to comply" with democratization promises made to their neighbors.

With congressional leaders of both parties at his side, Bush said, "We will be speaking with one voice," striking a sharp contrast to what was perhaps the most divisive issue of the Reagan administration.

The agreement provides for the continuation of non-lethal humanitarian aid through February 1990, the date set for elections in Nicaragua. Baker said it would amount to $4.5 million a month for 10 months.

"With regard to Nicaragua, the United States is united in its goals: democratization; an end to subversion and destabilization of its neighbors; an end to Soviet bloc military ties that threaten U.S. and regional security," the agreement said.

It noted that under existing agreements among the five Central American countries - Nicaragua, Honduras, El Salvador, Costa Rica and Guatemala - "insurgent forces are supposed to voluntarily reintegrate into their homeland under safe, democratic conditions."

The money provided under the agreement, expected to be approved by Congress soon after it returns from its Easter break next month, can be used for voluntary relocation aid, the agreement stated. Only the money, not the policy statement, needs congressional approval.

The two-page document was signed by Bush, House Speaker Jim Wright, D-Texas; House Minority Leader Robert Michel, R-Ill.; Senate Majority Leader George Mitchell, D-Maine; Senate Minority Leader Robert Dole, R-Kan.; and House Majority Leader Thomas Foley, D-Wash.

Baker denied that the payments amounted to "mustering out pay" for the Contras.

"There are no plans to request military assistance for the resistance, but there is no bar or prohibition to that in this agreement in the event that conditions should deteriorate substantially," Baker said.