UPDATE at 1 p.m. This post has been changed to reflect that political adviser Tom Goff says he hasn't been offered a job with a Dino Rossi campaign for Senate. We previously said Goff would play a key role in the effort.

WASHINGTON -- Republican Dino Rossi is hiring key campaign staffers and is expected to officially enter the U.S. Senate race against incumbent Patty Murray as early as Wednesday.

Pat Shortridge, senior strategist for Florida Republican Senate candidate Marco Rubio, has signed on to become Rossi's campaign manager, according to a person directly involved with Rossi's campaign. Shortridge, a political consultant based in Minnesota, was an aid to former House Majority Leader Dick Armey. Politico first reported that Shortridge has signed on with Rossi.

The person involved in the campaign said earlier today that Tom Goff, who worked on former Safeco CEO Mike McGavick's unsuccessful challenge against Sen. Maria Cantwell in 2006, would serve in a key role. However, the person now says it's unclear if Goff will be involved, and Goff said he hasn't been offered or accepted a job with Rossi.

Mary Lane Strow, Rossi's spokewoman during his first run for Washington governor, will work as part-time communications consultant.

Rossi has publicly toyed with the idea of running for the U.S. Senate ever since a GOP pollster in January reported that a race between him and Murray could be a statistical dead heat. Subsequent polls showed that Rossi could be competitive, despite Murray's edge.

Thanks to his two failed runs against Gov. Christine Gregoire, Rossi arguably is the state's best-known Republican. But he faces a dozen GOP rivals as well as Murray's formidable campaign account of $6 million on hand.