Residents will be able to register to vote and cast a ballot on Election Day starting next year under a measure given final approval Saturday by the state Senate.
The Democratic-controlled chamber voted 19-16, largely along party lines, to approve the measure, which Gov. Dannel P. Malloy has said he will sign.
The legislation also would allow potential voters to register online starting in 2014.
"The political reality is that voter interest peaks in the final weeks of any given campaign and current registration requirements prevent many eligible citizens from voting," said Sen. Gayle Slossberg, D-Milford, co-chairwoman of the legislature's Government Administration and Elections Committee.
Several voter advocacy groups, including the Brennan Center for Justice in New York City and Demos, a Washington, D.C.-based nonprofit, have reported that states allowing Election Day registration see at least a 10 percent boost in voter turnout.
Connecticut will join eight other states -- Idaho, Iowa, Maine, Minnesota, Montana, New Hampshire, Wisconsin and Wyoming -- that allow same-day registration.
Election Day registration would make voting easier, particularly for groups that tend to be more mobile, like young people, the poor and minorities, Slossberg added. Connecticut law currently requires potential voters to register at least seven days prior to the election.
But Republican senators argued that the same-day system would increase the risk of fraud.
Sen. Len Suzio, R-Meriden, relayed a message he got this week from the Democratic registrar of voters in his hometown that said: "Please vote 'no' to Election Day registration. It is pure insanity."
Letting people register to vote on Election Day would encourage people to be lax about registration, he said, adding, "they know they can come in and register at the very last second."
Sen. Michael McLachlan, R-Danbury, noted that in his home community, 10 percent growth in turnout would amount to about 2,000 new voters all needing to be registered on Election Day.
If it takes even 10 minutes to register each of these voters, it would translate to confusion and chaos in Danbury and likely in many other communities as well, he said.
"This is a major impact," McLachlan added. "This is a major activity that has never happened before."
But Democrats insist the necessary precautions are in place to avoid voter fraud. The new system will allow voters to show identification with an address before they can vote.
The House of Representatives, where Democrats also hold the majority, approved the bill 83-59 last week in another vote largely along party lines.
In a statement released after the Senate vote, Malloy praised legislators and said the bill will improve participation.
"Despite the pervasive climate across the U.S. to restrict voting rights, Connecticut has moved in the opposite direction -- one that ensures the integrity of our electoral process and fair, accessible elections," he said.