Section 4. The adoption of an optional plan of municipal administration under this chapter shall be initiated by filing with the board of registrars of voters of the city or town, a petition signed by at least ten per cent of the number of registered voters residing in such city or town at the preceding state election. Such petition may consist of a number of separate sheets, but each sheet shall be in substantially the form prescribed therefor in section five and shall be signed and completed in accordance with the instructions contained therein. The city or town clerk shall furnish forms for such petition to any registered voter of the city or town requesting the same. Within thirty days from such filing, the board shall check each name to be certified by it on the petition, shall certify thereon the number of signatures so checked which are names of registered voters in the city or town, and shall report the results to the city council in the city or town, or board of selectmen, as the case may be, by filing its report with the city or town clerk. Only names so checked shall be deemed to be the names of registered voters for purposes of such petition. The board need not certify more than one hundred and forty per cent of the number of names required to file a petition, and names not certified in the first instance shall not thereafter be certified on the same petition.

Objections to the sufficiency and validity of the signatures on any such petition as certified by the board of registrars of voters shall be made in the same manner as provided by law for objections to nominations for city or town offices, as the case may be.