SALEM — John Kitzhaber and Bill Bradbury go back quite a ways.

When Kitzhaber was governor, he appointed Bradbury as Oregon secretary of state when the office became vacant in 1999. They are close friends, so close that Kitzhaber jokingly dubbed the tall and lanky Bradbury the “Big Chinook,” after Bradbury’s advocacy of Oregon’s iconic fish.

These days, the two Democrats are rivals — both running for governor in the May 2010 primary in a race that could test a friendship that began nearly 30 years ago after both were elected to the Legislature from rural districts.

Kitzhaber is known as a blunt and scrappy maverick who at times frustrated even those within his own party with his go-it-alone ways while he was governor from 1995 to 2003.

During his years as secretary of state, from 1999 to 2008, and as a state legislator, Bradbury’s booming laugh and a love for politicking earned him a reputation as one of the most gregarious figures on Oregon’s political scene.

Bradbury is showing an eagerness to go toe to toe with his old pal for the Democratic nomination — perhaps in tacit recognition that Kitzhaber as the former governor has what many consider front-runner status at this point.

“Kitzhaber starts with a strong advantage,” says Portland pollster Tim Hibbitts. “Bill Bradbury will campaign as a happy warrior, and people will receive him warmly. But that doesn’t necessarily mean people will vote for him.”

The Republican contest features three lesser-known contenders — former businessman Allen Alley, state Sen. Jason Atkinson of Central Point and former legislator John Lim of Gresham.

How contentious the Democratic contest will become — if at all — is anybody’s guess, although both Kitzhaber and Bradbury insist they’re not going to let it wreck their friendship.

“The two of us have rafted most of the major rivers of the Northwest together,” Kitzhaber told The Associated Press. “He is a dear friend that I hold in great esteem. I can’t say a negative thing about Bill, and won’t.”

Bradbury says he isn’t worried that a tough race could spoil things between him and Kitzhaber. During Kitzhaber’s eight years as Oregon Senate president, Bradbury served six of those years as Senate majority leader.

“John and I are big boys,” says Bradbury, who ran unsuccessfully for the U.S. Senate in 2002 after Kitzhaber passed up a race against then-GOP Sen. Gordon Smith.

Bradbury makes it clear he’s not going to give Kitzhaber a free pass to the Democratic nomination.

While the two Democrats fundamentally agree on many key issues, especially around conservation and environmental protection, Bradbury takes aim at Kitzhaber on some points.

Bradbury notes that Kitzhaber as governor had indicated he would propose a tax plan to raise hundreds of millions of dollars for schools as well as provide stability for school finances, but Kitzhaber never came forward with such a plan.

And the former secretary of state points out the differing approaches that he and Kitzhaber took in launching their campaigns for governor.

Bradbury’s announcement came at a rally at Portland Community College, followed by appearances in six cities over the next 24 hours. Kitzhaber did no public event, choosing instead to post his announcement on his Web site. He followed up with interviews with selected news organizations.

“I’m out there, engaging and interacting with people,” Bradbury says. “You’ve got to earn that support; it’s not something you’re just entitled to.”

That comment reflects a feeling of unease that some in the party have about the perceived inevitability of Kitzhaber’s return to the governor’s office, says Russ Dondero, a political analyst and blogger whose own politics tend toward progressive Democrat.

Dondero makes another point that could have an impact on voters: since both have been in mainstream politics for years, the 62-year-old Kitzhaber and the 60-year-old Bradbury may have trouble selling themselves as politicians with fresh ideas.

“What I hear people say is, ‘Why don’t we have anybody else? Where is all of the new leadership?’ There are a lot of other talented people who for whatever reason are not getting into the race,” he said.

It’s possible others might jump in — Democratic Congressman Peter DeFazio is still considering the race, although the betting money is on him running for re-election to his House seat instead.

That means Kitzhaber and Bradbury are the two contenders, and it’s a choice that leaves some Democrats with mixed feelings about who they would like to see become the party’s nominee for governor.

Jim Edmunson, a former chairman of the Oregon Democratic Party and a former state legislator from Eugene, said that there’s a lot of affection for Bradbury, who over the years has been a war horse and cheerleader for the Democratic Party.

Kitzhaber, on the other hand, has in the past skipped national Democratic conventions and has never been one who enjoys political gatherings and backslapping, Edmunson said.

At the same time, Kitzhaber  — a former emergency room physician who was the architect of the Oregon Health Plan — has a certain mystique among many voters that probably gives him an edge, Edmunson said.

“The brain of the Democratic Party says John Kitzhaber is the man; he’s the former governor,” he said. “But the heart of the Democratic Party loves Bill Bradbury.”