Conn. Gen. Stat. § 9-428

(b) If a party-endorsed candidate for nomination to an office, prior to twenty-four hours before the commencement of the period of early voting at the primary, dies or, prior to ten days before the first day of such period of early voting, withdraws his name from nomination or for any reason becomes disqualified to hold the office for which he is a candidate, the state central committee, the town committee or other authority of the party which endorsed such candidate may make an endorsement to fill such vacancy or provide for the making of such endorsement, in such manner as is prescribed in the rules of such party, and certify to the registrar and municipal clerk or to the Secretary of the State, as the case may be, the name of the person so endorsed. If such certification is made at least twenty-four hours prior to the commencement of the period of early voting at the primary, in the case of such an endorsement to replace a candidate who has died, or at least seven days before the first day of such period of early voting, in the case of such an endorsement to replace a candidate who has withdrawn or become disqualified, such person so endorsed shall run in the primary as the party-endorsed candidate, except as provided in sections 9-416 and 9-417 . If such certification of another party-endorsed candidate has been made within the time specified in this section, and if the ballots have already been printed and the names of the candidates for such office appear on the ballots, the Secretary of the State or the registrar, as the case may be, shall direct the clerk of each municipality holding such primary to have the ballots reprinted with the name of the person so certified included thereon; provided, in the case of such an endorsement to replace a candidate who has died, if such certification has been made less than ninety-six hours but at least twenty-four hours prior to the commencement of the period of early voting at the primary, such Secretary or registrar shall direct such clerk to have stickers printed and inserted upon the ballots, having the name of the person so certified appearing thereon, and the moderator in each polling place shall cause such stickers to be pasted on the ballots before the opening of the polls at such primary. If no such certification has been made, such clerk shall cause the name of the candidate whose candidacy has been vacated to be obscured in such manner that such name is no longer visible.