Former Gov. Linda Lingle is expected to announce as soon as today that she will run in the Republican primary for U.S. Senate, sources say.

Lingle is scheduled to speak at a noon luncheon of the Sales and Marketing Executives International at the Pacific Club. The topic is how decisions made in Washington, D.C., can affect local businesses and the community.

U.S. Rep. Mazie Hirono, D-Hawaii, and former U.S. Rep. Ed Case are the Democratic contenders to replace U.S. Sen. Daniel Akaka, D-Hawaii, who is not seeking another term next year.

Most political analysts favor Democrats to hold the Hawaii Senate seat, since Democrats have a 24-point advantage over Republicans in party preference and have dominated island politics since statehood.

The Cook Political Report has Hawaii rated "solid Democrat," and the Rothenberg Political Report has rated the islands "safe Democrat."

But local Democrats believe Lingle will be competitive, and her entry into the race will bring national attention — and money — to Hawaii with Democratic control of the Senate at stake next year.

Lingle raised a record $6 million in her re-election campaign in 2006, and analysts believe that she could match that figure in a Senate campaign. Hirono and Case have never raised that amount of money for a campaign.

Lingle defeated Hirono in the governor’s race in 2002 after Hirono narrowly beat Case in the primary.

Republicans believe Lingle’s largest obstacle could be President Barack Obama. The Hawaii-born president remains popular in the islands and could help other Democrats on the ballot.

Lingle’s job approval rating fell at the end of her second four-year term after program cuts and teacher furloughs were used to help close the state’s budget deficit.