DUARTE'S PARTY CLAIMS VICTORY
President Jose Napoleon Duarte's Christian Democratic Party claimed an upset victory in national elections here today. President Duarte, speaking in an interview, said he believed his party had won at least 31 seats, giving it a majority in the powerful National Assembly. The contention was supported by a national exit poll carried out by the Spanish International Television Network. The poll, based on a survey of almost 11,000 voters, indicated that Mr. Duarte's party would win a majority of at least 32 seats in the country's powerful 60-member National Assembly. The Miami-based network conducted a similar poll after presidential elections here last year that was within four- tenths of one percentage point of the final result. Official returns from the contest for the National Assembly