* Democrat Daniel Akaka, 86, is retiring from Senate
* Lingle is heavily favored to win Republican primary
* Republican has set up her own cable TV station
By Malia Mattoch
HONOLULU, Aug 11 (Reuters) - Voters in Hawaii went to the polls on Saturday in a primary expected to set up Republicans for their first real chance at a U.S. Senate seat in the heavily Democratic state since 1970.
A victory by former governor Linda Lingle, who has an early edge in fundraising, in President Barack Obama's home state could also help Republicans take control of the U.S. Senate as they battle for a net gain of four seats.
While analysts expect Lingle to easily win her Republican primary contest, U.S. Representative Mazie Hirono and former Congressman Ed Case are locked in what is seen as a closer contest on the Democratic side to contest the Senate seat.
The seat is being vacated by Senator Daniel Akaka, a Democrat who at age 86 is retiring after 22 years in the Senate.
Hawaii has never voted out a sitting U.S. Senator, so the retirement of Akaka creates a rare political vacuum in the state that Lingle and the GOP are hoping to exploit. The last time Republicans won a U.S. Senate contest was in 1970, when then-Senator Hiram Fong won re-election.
Lingle, who served as governor of Hawaii from 2002 to 2010, has raised over $4.4 million compared to Hirono's $3.4 million and Case's $819,000, according to figures from the non-partisan Center for Responsive Politics.
Sixty-five percent of Lingle's donations, a total of nearly $2.2 million, come from outside Hawaii, the group said.
"The GOP thinks she has a chance and this election has national implications because of the narrow margin of party control in the Senate," said analyst Neil Milner, a retired University of Hawaii political science professor.
Hawaii residents can tune in from home to a constant reminder of Lingle's successful fundraising. The candidate has taken the unusual step of securing her own cable station in the state, sandwiched between the CNN and Fox channels. It runs around-the-clock information on Lingle and her campaign.
Polls show Lingle running behind either Hirono or Case, the two Democrats, in a hypothetical match-up. A Honolulu Star-Advertiser poll conducted in July by Ward Research showed Hirono leading Lingle by 58 percent to 39 percent, and Case ahead by 56 percent to 38 percent.
But observers note Lingle beat Hirono in the 2002 race for governor, after Hirono defeated Case in that year's Democratic primary to seek the state's top office.
"Because Lingle has already defeated Hirono in a head-to-head match-up, many observers see a Hirono victory today as a Lingle victory in November," said University of Hawaii Law Professor Randy Roth.
Polls showing Lingle trailing the two Democrats in a hypothetical match-up were similar at the same point in the 2002 race for governor, which Lingle ultimately won, Roth said.
The July Ward Research poll gave Hirono a double-digit lead over Case - 55 percent to 37 percent - but other polls indicate a closer race between the two Democrats.
News organization Honolulu Civil Beat, in a poll conducted two weeks ago, gave Case a one-point lead over Hirono - 47 percent to 46 percent.
Hirono is seen as an establishment Democrat. If she were to win in November she would be the nation's first female Asian U.S. Senator. Case appeals to more fiscally conservative Democrats and independents, but he infuriated traditionalists in the state here when he challenged Akaka for his seat in 2006.
On the Republican side, Lingle faces four primary opponents. Perhaps the most well-known contender is former state legislator John Carroll, but analysts do not expect any of them to give Lingle a real challenge in Saturday's primary.
Milner predicts outside Democratic money will start to pour into the winning Democratic camp once the primary is decided. (Editing by Alex Dobuzinskis; editing by Todd Eastham)