A national organization representing independent voters is calling for the Democratic Party of Hawaii to withdraw its federal lawsuit that seeks a closed primary election system.

The lawsuit filed in federal court last month claims Hawaii’s primary system that allows every registered voter to participate in the party’s nomination process is tantamount to forced political association and is unconstitutional.

The lawsuit caught the attention of New York-based IndependentVoting.org, prompting the group to take out an ad that will be running in Sunday’s Honolulu Star-Advertiser. The ad says requiring party registration would end political privacy.

“So many Americans are concerned and upset about the issue of partisanship,” Jacqueline Salit, the group’s president, said today. “It’s becoming a hot-button issue around the country.”

The lawsuit would narrow the democratic process and goes against Hawaii’s spirit of openness and inclusiveness, Salit said. While there have been similar attempts by Republicans, “this is the first time in recent history that a state Democratic party has taken this action,” she said of going to court to change the primary system.

The half-page ad was paid for by donors in Hawaii, she said. The ad says the lawsuit highlights a divided party, noting that Gov. Neil Abercrombie and other Democratic elected officials said they support open primaries.

The lawsuit isn’t about excluding voters but ensuring Democrats are selected at the primary stage by those willing to identify as Democrats, party Chairman Dante Carpenter said. “The primary is literally about selecting the candidate for the party,” he said.

“We know that most people don’t want to belong to a political party and that’s OK, we respect that,” he said. “But we do respect someone who is willing to openly make a selection and not be afraid to tell the world about it.”

Carpenter said that helps eliminate the trickery that goes on, when someone votes for a less desirable candidate to improve the chances of a candidate in another party. “So that when the candidates vie against each other in the general election, they’re the best possible candidates.”