A study commissioned by the non-partisan voting rights group Mass Vote says same-day registration could lead to a sharp jump in turnout on election day. The study, conducted by researchers at Cal-Tech and NYU says had election day registration been in place in Massachusetts during the 2004 presidential election, more than 225,000 additional votes would have been cast. A measure that would allow a test of same-day registration this November has been approved by the legislature’s election laws committee. City and town clerks have been wary of the idea because of potential strains on their staff and added costs — issues that Mass Vote Executive Director Avi Green says can be overcome. Secretary of State William Galvin has said Massachusetts would need as many as 4200 additional poll workers to help register new voters on election day.