The Senate completed action yesterday on legislation providing $4 billion in federal guarantees to the shaky Farm Credit System but delayed a final vote on the measure until Friday.

The vote, which would clear the measure for action by House-Senate conferees, apparently was delayed at the request of absent Minority Leader Robert J. Dole (R-Kan.), who was campaigning in Iowa for the Republican presidential nomination.

Agriculture Committee Chairman Patrick J. Leahy (D-Vt.) told the Senate that, even with the delay, there is "a real possibility" that Congress could send the bailout package to the White House before year's end.

"The speed with which the Senate acted on this legislation indicates how important we believe it is to restore confidence in the FCS," he said after less than two days of debate.

Leahy indicated in an interview that, in the event of further delays, conferees could complete their work early next year without harming the farmer-owned banking network.

The Senate measure would authorize the system to sell as much as $4 billion worth of federally backed bonds to help distressed FCS district banks recover from a rash of heavy losses related to low farm prices and falling land values.

Interest on the bonds, which could reach $1.2 billion, would be paid by the federal government during the first five years of the rescue program. Interest costs would be shared by the Treasury and the FCS during the next five years.

An amendment added yesterday by Budget Committee Chairman Lawton Chiles (D-Fla.) and ranking GOP member Pete V. Domenici (N.M.) would require the FCS to repay the interest subsidies to the Treasury if the system returns to profitability.

In return for the federal guarantees, the FCS would be required to streamline and consolidate its nationwide banking system, and FCS borrowers would be given new protections in restructuring debts and repurchasing foreclosed farm properties.

The legislation also would provide federal guarantees for a new secondary market in farm real estate and extend new rights and protections to farmers doing business with the Farmers Home Administration.