The center of gravity in Hawai'i's 2006 election has just tilted toward the Democratic primary in September, and that unpredictable force may tug the state Legislature in some unexpected directions.

When U.S. Rep. Ed Case announced Thursday that he will challenge fellow Democrat U.S. Sen. Daniel Akaka, what was widely expected to be a routine and successful Akaka re-election effort was instantly converted into the most exciting primary race in the state.

It also set up a surge of candidates yesterday into the Democratic primary to fill the U.S. House seat that Case will vacate, with state Sens. Gary Hooser and Ron Menor and state Rep. Brian Schatz announcing they will run.

Former Lt. Gov. Mazie Hirono and state Sen. Colleen Hanabusa have also confirmed they intend to run.

By itself, that rush from the Legislature into the U.S. House race won't trigger much change at the Hawai'i Capitol because the state senators who joined the race are not up for re-election this year.

If they fail to win the U.S. House seat, all of them will return to their state Senate seats to serve out the remaining two years of their terms.

Only Schatz, D-25th (Makiki, Tantalus), will be unable to return to the Legislature after the federal campaign because his state House term ends this year.

What might affect the makeup of the Legislature more will be turnout at the polls — the rush of Republican and independent voters who want to participate in the hard-fought Democratic primaries for the U.S. Senate and U.S. House, said state Sen. Paul Whalen, R-3rd (Kohala, Kona, Ka'u).

"Normally the Democrat primaries are pretty much controlled by the public unions and unions in general because they get out the vote, and the average guy in the street tends to ignore the primaries," Whalen said. But with the "extremely heated" federal races, general voter turnout for the Democratic primary will jump.

With so many non-Democrat voters joining in the Democratic primaries, Whalen said that will dilute the influence of Democratic Party insiders and "power brokers, and in some races the outcomes may change," he predicted.

"I think it will bring the vote more toward the average guy instead of just the special interests," Whalen said.

House Majority Leader Marcus Oshiro agreed that non-Democrats will be eagerly voting in the Democratic primary, with Case wooing independents and the moderate Republicans.

But Oshiro believes a good overall turnout and an exciting contest will be good for Democrats overall because it will help mobilize the Democrats' base.

"To me that is a plus," he said. "Democrats have always come together to support one candidate going into the general, and that has been our strength."

Hooser and Menor opted for haste over ceremony as they both officially announced their candidacies for the congressional seat less than 24 hours after Case's announcement.

Campaign signs were absent and neither press conference drew many supporters. Only Menor offered a written statement. Hooser directed reporters online if they needed more information.

Hooser, D-7th (Kaua'i, Ni'ihau), brought a handful of supporters with him to the brief press conference he held at the Laniakea YWCA in between legislative hearings. He was unable to fly his family in from Kaua'i to be present for the 1 p.m. announcement.

However, he made it clear that he had been considering the race well before Case made his intentions official. "I've been thinking long and hard about this the past couple months, actually," he said, noting that rumors had been floating about in political circles for the past six to eight months.

Because the congressional district is largely Neighbor Islands, Hooser said his representation of Kaua'i will help him understand uniquely rural issues, such as preservation of agricultural lands, open space and access to beaches.

At 2 p.m., Menor, D-17th (Mililani, Waipi'o), was able to produce his wife for his announcement but not his children, who were still in school. He held his press conference in front of the Halekauwila Street entrance to the Prince Kuhio Federal Building.

Menor, who lives in the 2nd Congressional District on O'ahu, pointed out that he was born and raised on the Big Island.

Menor, the chairman of the Senate Commerce, Consumer Protection and Housing Committee, said his 22 years of experience in the Legislature set him apart and he pointed to several pieces of legislation he has authored, such as the gas cap bill and the Hawaii Rx Plus prescription drug reform law.

Menor said that if he is elected, "You can rest assured I will continue to stand up on behalf of consumers against big oil and large pharmaceutical companies."

Also declaring his plans to run yesterday was Schatz, who said he has an advantage at age 33 because of his youth.

"Hawai'i voters are very akamai, and they know that you need to develop tenure, and I'm unique as a candidate because I could put in 10 or 20 or even 30 years in the House of Representatives to really put Hawai'i in a strong position in the Congress," he said.

Schatz, who is vice chairman of the House Water, Land and Ocean Resources Committee, said rapid growth on the Neighbor Islands will make environmental issues a "critical" part of the campaign.

Whalen said a large number of Democratic candidates in the U.S. House primary will tend to splinter the vote.

"The more guys that run, the harder it's going to be for all of these guys in the primary," he said. "I'm sure this weekend the phone lines will be buzzing trying to organize the support and commitments from the party, whatever they feel they can get."

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.