The party's executive committee will consider the plan Jan. 5. If approved by a majority of the committee's 50 members, it would then go to state party members for a vote, state GOP Chairman Giovanni Cicione said.
The Republican and Democratic parties currently allow unaffiliated voters to opt into either party on primary day to cast a ballot. Democrats outnumber Republicans nearly four-to-one in Rhode Island, with about 287,500 registered Democrats compared with 72,800 registered Republicans, according to the secretary of state's office. Those are both smaller than the roughly 335,300 unaffiliated voters.
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The rule became an issue in 2006 when then-Republican Sen. Lincoln Chafee, a moderate, was embroiled in a primary with a more conservative challenger, former Cranston Mayor Steve Laffey. Mr. Chafee urged Democratic supporters to drop their party affiliation to vote for him. Mr. Chafee won the primary but went on to lose the general election to Democrat Sheldon Whitehouse.
The bitterly contested primary still is a sore spot for some conservative Republicans, who had dubbed Mr. Chafee a RINO - Republican in Name Only. Darrell West, a political scientist at the Brookings Institution and former professor at Brown University, said the primary drew a large turnout of unaffiliated voters who propelled Mr. Chafee to victory.
"If it hadn't been for independents, Laffey would have won that primary," he said.
The proposal comes as Mr. Laffey is being urged by many supporters to run for governor. The Republicans' only declared candidate, Rory Smith, dropped out of the race this month, and the party has been casting about for another contender. Laffey supporter Raymond McKay, an executive committee member, is leading the push to close the primary.
Mr. McKay, president of the conservative Rhode Island Republican Assembly, said he has been pushing for the change since 2004, but what happened with Mr. Chafee's campaign in 2006 helped fuel the drive.
"The reality of the issue is that people did cross over to weigh in on a Republican primary, and they weren't Republicans," he said. "It's horrendous. It's tampering."
Mr. McKay said he has commitments from 25 of the executive committee's 50 members to support the proposal. If it passes, Mr. Cicione said the plan would then have to be read at a state party meeting and voted on by the party's 250 members at a second meeting. The next party meeting is scheduled for February.
Mr. Cicione said he's not sure yet whether he supports the measure, but said he would not want it put into place until the 2012 race because it's too soon before the September primary. Mr. McKay said there are ways to speed up the measure so that it could be decided by February.
Mr. Chafee has since left the Republican Party and plans to officially announce his run for governor as an independent on Monday.
Mr. Laffey did not immediately respond to requests from AP for comment on whether he supports the idea.
But John Robitaille, a senior adviser to Republican Gov. Don Carcieri, who said Tuesday he also is considering a run for governor, thinks the idea is bad for the party. He said the current system allows candidates to reach out to a broader audience during the primary.
"If you only look at people who are registered Republicans having a say, your chances of having a good candidate who could actually win in the general election is skewed," he said.
Warwick Mayor Scott Avedisian said he also opposes the idea.
"I think the only way a party grows and continues to thrive and bring more people in is to have an open primary system," he said. "We need an infusion of new ideas and new people, or nothing's going to change."
Among the 41 states that had primaries in the 2008 presidential election, they were about evenly divided between those that have open and closed primaries, according to a report by the Pew Center on the States.
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