MINNEAPOLIS (AP) _ Delegates from three Lutheran churches are expected to affirm a merger of their denominations later this spring, following approval by congregations of the American Lutheran Church, officials said Friday.

The new church to be created by the merger of the three denominations, which represent 5.5 million people, is to be called the Evangelical Lutheran Church of America.

Eighty-one percent of the members of the Minneapolis-based ALC voted to approve the merger of the ALC and two other Lutheran groups, ALC Bishop David W. Preus said Friday. The vote was taken between Sept. 15 and March 15.

The two other groups, the New York-based Lutheran Church in American, and the St. Louis-based Association of Evangelical Lutheran Churches, have also tentatively approved the merger.

The church is to be based in Chicago and will begin operating next Jan. 1.

The 1,045 delegates of the three churches will meet April 30 for a four-day convention in Columbus, Ohio, to formally affirm the merger and elect a bishop and other church leaders.

The only vote that could jeopardize the merger is one scheduled April 29 by more than 500 delegates of the LCA. In August, the LCA approved the merger in its first ballot of delegates, but a second ballot is required under the church's constitution, said the Rev. Ralph Eckard, assistant to the LCA bishop in New York.

''It is a formality and yet it is an absolute requirement,'' Eckard said Friday in a telephone interview. ''Actually, the delgates could vote not to procede with the merger but that is a very, very remote possiblity.''

Preus said that out of 4,660 valid ballots cast by ALC congregations, 3,752 voted yes, 863 voted no, and 45 abstained. A two-thirds vote was needed to ratify the merger.

''The more than four-fifths favorable vote indicates the strength of the ALC desire for union,'' Preus said in a statement. ''Having voted their best judgment, the congregations will now pull together, worshiping and serving God in and through the Evangelical Lutheran Church in America.''