Daddario Will Seek Senate Seat of Dodd By JACK ZAIMAN ' U.S. Rep. Emilio Q. Daddario of Hartford has decided to seek the Democratic nomination for the U.S. Senate seat held by Sen. Thomas J. Dodd. He is deferring a formal announcement o f candidacy pending a declaration by Gov. Dempsey on whether he will seek renomination to the gubernatorial post he has held since 1961. ' Gov. Dempsey's announcement is expected within the next two or three weeks. Most observers expect him to run again. In the unlikely event that he does not, then Rep. Daddario may' switch signals and run, instead, for governor. In line with his decision to seek the Senate nomination, Rep. Daddario already has begun a statewide tour to determine the Democratic party situation in a number of areas. His decision to run for the . Senate is expected to lead to support from the state party organization led by S t a t e Chairman John M. Bailey, who thus far has remained silent in the boiling Senate nomi nation controversy. :.S The Hartford party organization led by Town Chairman J. Michael Kelly is expected shortly to move behind Daddario for the Senate, and other pro-Daddario moves are under way. The only announced candidate for the Senate nomination is Joseph Duffey of Hartford, national chairman of the Americans f o r Democratic Action. On Thursday, Slate Sen. Edward L. Marcus of New Haven will announce his Senate candidacy at a breakfast press conference at the New Haven Motor Inn. Sen. Dodd has repeatedly said he will seek renomination, although he has not made a formal declaration of candidacy. Also mentioned for the Senate are Mrs. Ella Grasso of Windsor Locks, secretary of state, who is close to the Dem-psey-Bailey party leadership; ' Alphonsus Donahue of Stamford, a businessman, and former Mayor Richard C. Lee of New Haven, who left office Jan. 1 with an annual disability pension of $13,000. The word that Daddario is running for the Senate coincided with his return to Connecticut following the congressional session that ended last week. - Almost immediately, it was learned, Daddario began a series of conferences with his supporters on hia Senate candidacy. v : His decision to run was made following weeks of talks with state and regional party leaders, including Gov. Dempsey. The Governor also talked with a numner or other Senate aspirants, 'ncludinp Marcus, Lee, Duffey and Donahue. He gave vj .joiunitment to anyone op me Supte, nor did he give anv clues whether he will run aam. , 4 : Nearly ?vervnne in the party expects nim to be the standard bearer again this year, but there is just enough doubt to cause some hesitation here und these One party leader put it this way: "I am 98 per cent convinced D f. m o s e y will run again. But that remaining 2 per cent worries me." The Democratic state nominating convention will be June 26 and 27. at the Bushnell Memorial.