Republican Tom Coburn of Oklahoma is not expected to face much of a challenge, either in Tuesday’s primaries or in November, in his bid for a second term in the U.S. Senate.

Oklahoma is widely regarded as a safe state for Republicans in national elections. The last Democrat the state sent to the Senate was David Boren, who stepped down in 1994 to become president of the University of Oklahoma.

The two Republicans, two Democrats and two Independents who filed to run for Coburn’s seat in 2010 are all relatively unknown, inexperienced or underfunded candidates.

Coburn, a 62-year-old doctor from Muskogee established considerable political formidability winning three terms in the U.S. House of Representatives between 1994 and 2000. After four years on the sidelines, Coburn returned to politics in 2004 with an easy win over former Oklahoma City Mayor Kirk Humphreys in the GOP primary for the Senate seat vacated by Don Nickles, and went on to defeat Democrat Brad Carson by a solid margin in the general election.

More than a decade immersed in the politics of the nation’s Capitol has done little to change the senator’s prized self-image as a political maverick and Washington outsider. He was openly disdainful of career politicians in his book “Breach of Trust” and remains so today.

“Anyone who knows me knows I’m the ultimate noninsider,” Coburn said in a recent telephone interview. “I challenge Republicans and Democrats alike.”

He blasts federal officials and the bulk of his colleagues in Congress for being careerists with “no real world experience.”

“The problem we have here in Washington is that these people have never done anything else in their lives,” Coburn said.

The senator prides himself in having continued his medical practice in Oklahoma throughout his two tenures in Congress. A proponent of term limits who kept a campaign promise not to seek more than three terms in the House, Coburn says this will be his last term as a senator as well.

Coburn is a fiscal and social conservative with a reputation for opposing pork barrel projects and any measures he views as deficit spending. He cites $110 million in annual Medicare fraud, 70 programs to feed the hungry “with no metric on them” and $10 billion in travel expenses of federal employees that could easily be reduced to $2 billion as examples of wasteful spending.

“The American people need somebody who’s going to stand up and say, ‘If we’re going to create new programs, we must eliminate programs that are not as important,’” Coburn told the Globe.

Lewis Kelly Spring, of Hugo, and Evelyn Rogers, of Tulsa, are the two Republicans who took out papers to challenge Coburn in the primary. Little is known about Rogers, who did not return calls from the Globe seeking information about her candidacy.

Spring, 62, a retired special education teacher, decided to run after hearing Coburn speak at a town hall meeting. He said he considers the senator “a fake Republican.” Spring went to the meeting in Hugo with favorable inclinations, he said, since Coburn was touted as a strong Christian conservative. But he left disappointed, he said.

“He’s got no ideas on how to fix our republic,” Spring said. “He’s got no ideas on how to fix our economy.”

Spring will not accept any campaign contributions and has spent $1,500 of his own money filing to run and setting up a website. But he says “there’s a lot of unhappiness with incumbents.”

Spring’s primary political desire is to see the federal reserve banking system abolished. He views the system as the source of the nation’s economic woes and believes “a declaration of Jubilee, the abolishment of the federal reserve and the IRS, along with the establishment of the ‘Bank of the American People,’ will save us from the economic ruin that is upon us.”

Democrats

Mark Myles, an attorney from Oklahoma City specializing in criminal and administrative law, and Jim Rogers, an oil rights and land leaser from Midwest City, are the two candidates in the Democratic primary. Neither has held an elective office previously, although Rogers ran for Sen. James Inhofe’s seat two years ago and received about 40 percent of the vote in the Democratic primary.

Rogers, 75, was reluctant to discuss much about his candidacy during a telephone interview but later sent a letter to the Globe expressing concerns with identity theft and alleged treatment by the government during his candidacy two years ago. He told the newspaper he holds a bachelor’s degree in chemistry and mathematics from Oklahoma Baptist University and master’s degrees in physics and as an education specialist from the University of Wyoming.

Myles, 54, is a graduate of Oklahoma State University who obtained his law degree from the University of Oklahoma two years ago. He describes himself as a fiscal conservative and social moderate who hopes to survive the primary and battle Coburn this fall despite having raised less than $5,000 for his campaign to date.

Myles believes that Coburn’s claims to remaining a Washington outsider are disingenuous.

“He knows how to pull the levers and get what he wants,” Myles said. “He knows how to shut down things. He’s been kind of an obstructionist.”

Coburn has used the hold privilege of senators to block bills from reaching the Senate floor, most prominently some whistleblower protection legislation that had bipartisan support and a veterans health benefits bill.

Myles criticizes the senator for more recently having a hand in holding up the extension of unemployment benefits. He accuses the senator of also hurting his  home state in terms of federal assistance for interstate highway and Corps of Engineers projects.

“These are core functions of government,” Myles said.

Myles said he realizes his chances of upsetting Coburn are slim, but he wants to give Oklahomans a choice in the fall.

“Our system of democracy doesn’t work if we don’t have people who’ll contest elections,” he said.

Independents

The two candidates running as Independents in the primary, Stephen F. Wallace and Ronald F. Dwyer, both of Tulsa, did not return repeated calls seeking information about their candidacies.