Chase Manhattan Corp., as part of its proposal to acquire the troubled Merritt Commercial Savings and Loan Association, has agreed to purchase a 29-story office building being built by the thrift in downtown Baltimore, but is asking the state to reimburse it up to $20 million if the bank should suffer losses by assuming Merritt's loan portfolio, according to sources familiar with the offer.

The sources said the prospective deal allowing Chase to buy Merritt and two other healthier thrifts in Montgomery and Anne Arundel counties would strongly benefit the giant bank by giving it a major presence in the state, while relieving Gov. Harry Hughes' administration of a large share of its savings and loan troubles.

"It's a great deal for the state. It's a great deal for everyone," said one source knowledgeable about the offer from Chase, the nation's third-largest banking company with $86.3 billion in assets.

It could not immediately be determined how much Chase has offered for Merritt, but the offer does include the purchase of the $43 million tower being constructed by the Baltimore thrift in the heart of the city's financial district.

Chase is also asking the state to indemnify it for as much as $20 million in potential losses from assuming Merritt's assets, which include a high percentage of construction and land development loans.

Merritt, which voluntarily was placed under state conservatorship in May, is generally regarded to be more financially sound than the other thrift under conservatorship, Old Court Savings and Loan.

If the losses did occur, Chase would be repaid by funds from the $160 million insurance pool now controlled by the Maryland Deposit Insurance Fund.

Sources said Chase would be far less likely to suffer losses in its proposed acquisition of the two other thrifts, Chesapeake Savings and Loan Association of Annapolis and Friendship Savings and Loan of Bethesda, which have assets of $100 million and $340 million, respectively.

Officials at those two thrifts declined comment yesterday on Chase's offer, but the sources said Chase had made "generous" offers to acquire the institutions. In Chesapeake's case, for example, Chase offered roughly $4 million for the thrift, an amount equal to 1 1/2 times the association's net worth, sources said.

Hughes administration officials said little publicly yesterday about the Chase proposal. Ejner J. Johnson, Hughes' chief of staff, said the administration is "cautiously optimistic" about a possible purchase of Merritt. But, he added, "We have a long way to go."

However, other sources said that Hughes met late yesterday with Chase officials to go over details of the offer and that the governor was planning a major announcement encompassing the bank's offer and other developments as early as next week.

Expected to be included in that announcement is word that several other of the state's largest thrifts have won conditional approval for federal insurance and a resolution to lingering questions surrounding First Maryland Savings and Loan of Silver Spring.

First Maryland's president, Julian M. Seidel, who said recently that his thrift would have to raise as much as $15 million to meet a key requirement for federal insurance, has been under increasing pressure from the state to resolve his association's status.

First Maryland has borrowed approximately $6 million from MDIF since the agency was formed in late May, according to sources.

Sources said that Seidel is being pressured by state officials to discuss a merger with other financial institutions. Seidel could not be reached for comment yesterday.

In other developments yesterday, Slavie Savings and Loan Association of Baltimore, with $37.9 million in assets, and Severn Savings Association of Annapolis, with $21.5 million in assets, received final approval for federal insurance, bringing to 16 the number that have moved into the federal system since May.