Del. Robert D. "Bobby" Orrock Sr. stood on the front porch of a Spotsylvania rambler and began his standard campaign pitch, but the man standing in the doorway flashed the Republican lawmaker a knowing look.

"Oh, hey, Bobby, I know your son," he said. The two men chatted for a minute, and then Orrock quipped about his namesake.

"In spite of knowing Bobby, I hope you vote for me," he said, moving on to the next house.

Easygoing conversations with old acquaintances are hardly rare for the delegate in his Republican primary campaign. The name recognition and personal relationships enjoyed by longtime politicians such as Orrock represent a daunting challenge for those who would unseat them.

Down one street, a former student of Orrock's at Spotsylvania High School comes out to greet the lawmaker. Down another, an afternoon jogger needs no introduction: "I know you very well, delegate."

Orrock, 49, is one of a half-dozen GOP delegates who face primaries largely because they broke with their legislative leaders last year and supported tax increases backed by Democratic Gov. Mark R. Warner.

After the General Assembly session, anti-tax conservatives within the party swore revenge against the mavericks. But the primary campaigns are testing their counter-revolution against delegates who have a combined 70 years of legislative experience.

Shaun V. Kenney, Orrock's challenger, was an aide for the eight-term delegate several years ago. Now he is trying to rally conservative voters over Orrock's support for the tax increases and his stances on social issues. Kenney, 27, said the positions are out of step with the 54th District, a rapidly growing area that last year voted overwhelmingly for President Bush.

And he has a different spin on his opponent's incumbency: He said it has distanced the veteran lawmaker from his district.

"Bobby hasn't had a serious challenger in 12 years, and I think these votes show that he's out of touch," Kenney said. Orrock has never run in a primary race, and he last faced a general election challenger in 1995. Although Kenney remained upbeat, he acknowledged that a tough road lay ahead in pursuit of an upset.

"Challengers have a hard go, and Bobby's got me outspent four to one," said Kenney, who had $26,569 on hand as of the last filing, on March 31, compared with Orrock's $116,703. "But conservatives around here are not stupid, they're not blind. . . . They've paid attention" to Orrock's record.

Orrock has said the tax increase was necessary to fund such services as education and to ensure that the state had a budget last year.

Orrock not only is a teacher but also is a Sunday morning disc jockey at a radio station. A native of Fredericksburg -- just north of his district, which encompasses parts of Spotsylvania and Caroline counties -- he volunteers on the rescue squad Friday nights in Caroline.

Although he knows these are advantages, Orrock insists that he is not taking Kenney for granted. Last weekend, for instance, he held a campaign event at a fairground, where residents listened to music, ate hotdogs and talked politics.

"I hate to be arrogant, but they're going to be hard-pressed to get me," Orrock said recently at the end of an afternoon knocking on doors. "It's not impossible, but they'd be hard-pressed."

Each of the delegates has a lot more campaign money than his challenger. In Lynchburg, Del. L. Preston Bryant, leader of the House mavericks last year, had $200,000 in campaign funds as of March 31. His opponent, Robert Garber, had $226. Fundraising by GOP incumbents in Northern Virginia outpaces that of challengers by 3 to 1.

In many cases, the contributions challengers have received have come from outside their respective districts. In his race against Del. Joe T. May (Loudoun), for instance, Christopher G. Oprison had a handful of contributions of more than $100 from within the 33rd District as of March 31.

In addition, House GOP leaders have campaigned for several maverick delegates, sending a signal to voters that they should support the incumbents.

The Virginia Conservative Action political action committee has been a major source of funding for most of the challengers.

"It's very, very hard to challenge incumbents, we knew that from the beginning," said Robin DeJarnette, executive director for the PAC. For every dollar that challengers receive from VCAP, incumbents are getting more from Leadership for Virginia, a PAC organized to protect the delegates who supported the tax increases.

But the challengers point to recent history as their guide. Several said they hope to replicate the success of Del. Jeffrey M. Frederick (Prince William), who beat longtime delegate John A. "Jack" Rollison III in the 2003 GOP primary.

Kenney, who serves as committee chairman of the Spotsylvania County GOP, points out that he has received organized support from party activists, which will help him on in the primary June 14. In fact, several of the challengers have received support of their local political committees or their chairmen.

The challenger also said he has tried to counter Orrock's visibility through radio ads, targeted mail pieces and knocking on as many doors as possible. Many challengers limit themselves to Republican voter lists in deciding where to focus their attention.

"I believe if I can hit as many houses as possible, work places that don't know my name, I can get there," Kenney said as he walked several Spotsylvania streets on a recent afternoon. "This is hard, but it's not impossible."