Here’s a sure sign that commercial real estate broker Chris Riggs is planning to challenge Rep. Ken Calvert in the Republican primary next year: Riggs in recent days has launched Twitter and Facebook sites, and he has also begun to hire consultants and campaign staff.

“This race will be a litmus test to see if all the millions of tea party’ attendees across America are really serious about electing officials that run on a limited government, tax lowering platform, as this will be a perfect opportunity to pick off a big tax-and-spend incumbent,— Riggs told the Orange County Register this week.

Riggs is also painting himself as an outsider bent on toppling an ultimate political insider who has spent 17 years in Congress and has been accused of improperly profiting from local land deals.

Until recently, Calvert seemed unbeatable in his Riverside-Orange county district. But last year, he finished less than 3 points ahead of his Democratic challenger, Bill Hedrick. Hedrick, a local school board official, is trying again in 2010 — and this time he’ll have the support of national Democrats, which he lacked last cycle.