Cindy Ellen Russell/Honolulu Star-Advertiser/AP Photo

First, it was President Obama’s Senate seat in his hometown of Illinois that Democrats lost. Now, they are in danger of losing a key seat in the president’s birthplace of Hawaii, which could jeopardize their senatorial majority.

As Obama touches down in Hawaii this weekend, a political battle is brewing to replace longtime Democratic Sen. Daniel Akaka, 87, who retires next year at the end of his term.

Republican Linda Lingle, a former two-term governor, has emerged as a formidable force, running neck and neck with Democratic contenders Rep. Mazie Hirono and Ed Case, a former congressman.

Losing Akaka’s seat, which he’s held for more than two decades, would be a major blow to Democrats. Since it became a state in 1959, Hawaii has elected a Republican senator only once – Hiram Fong in 1959 – and a Republican House representative only twice. Currently, all four of its delegates – two in the Senate and two in the House – are Democrats.

Losing Akaka’s seat would also endanger Democrats’ majority in the Senate. They narrowly held on to power in 2010, and have 23 seats to defend next year, compared with 10 for Republicans.

“If they’re losing Hawaii, they’re losing the Senate,” said Jennifer Duffy, a political analyst at the nonpartisan Cook Political Report. “I think that it would be hard to lose Hawaii and not be losing three or more seats elsewhere.”

The Cook Political Report changed the race from a solid Democratic win to a toss-up when Lingle announced her candidacy last month.

Lingle left the governor’s house with an approval rating of 44 percent, lower than her previous ratings but still higher than the current job approval of Democratic Gov. Neil Abercrombie.

Hawaii may be a blue state but Lingle, whose gubernatorial term ended last December, enjoyed hefty support in her time as governor. She won two out of three governor’s races and is popular among independents, a key voting bloc.

“Hawaii is a really tough state for Republicans. At the same time Republicans have a candidate who has been successful statewide,” Duffy said. “If voters are angry at Washignton, then I can certainly see them perhaps looking at her as somebody who might be more willing to come to D.C. and try and get some things done.”

Lingle has also won the support of some Democrats, who were upset with Case for challenging Akaka in the 2006 election. She will need to continue attracting swing voters – as she did eight years ago – to deliver a victory in 2012.

The former governor knows a few things about running in a state that’s light on conservatives. Lingle emphasized in her candidacy announcement that she wouldn’t be bound to either party when in Washington.

“I want to be real clear on this point: I don’t work for [Senate minority leader] Mitch McConnell and for that matter I don’t work for President Obama. I work for the people of Hawaii. And if there’s a law being proposed …  if it’s good for Hawaii, I’m for it. If it’s not good for us, I’m against it, regardless of who introduces it.”

But the road to the Senate is not going to be an easy one for Hawaii’s first female governor. Democrats are already linking Lingle to former Alaska Gov. Sarah Palin, who appeals to many conservatives but hasn’t gained a big mainstream following. Lingle introduced Palin at the Republican National Convention in 2008.

Democrats are also likely to attack the budget cut measures Lingle implemented as governor. Lingle instituted  an unpopular school furlough program that sparked contentious protests.

Lingle will also have to overcome the challenge of having Obama on the ticket. The Hawaii native remains highly popular in the state and is likely to pull a strong group of Democratic supporters to the polls.

“The general election will not be easy for Lingle, regardless of whom the Democrats nominate. The 2010 Republican wave never came ashore in Hawaii,” according to the Cook Political Report’s analysis. “Whether she can overcome the challenges of running in a presidential year isn’t yet clear, but she will make this a race that Democrats hadn’t counted on having.”

As of now, Lingle will face former state senator and unsuccessful gubernatorial candidate John Carroll in the primary. Case and Hirono will compete for the Democratic slot.

Lingle has already been pitted against the Democratic challengers before. She defeated Hirono in the 2002 gubernatorial race  in which Case also ran for the Democratic candidacy.

The year 2012 is going to be a challenging one for Democrats, who lost key Senate seats to Republicans last year. Republicans picked up six Democratically controlled seats in 2010, including Obama’s Illinois Senate seat. Earlier that year, Scott Brown delivered a major blow to Democrats by winning the Massachusetts Senate seat that was occupied by liberal icon Ted Kennedy for nearly 47 years.