The sign on the door of Theresa Dudley's fourth-grade classroom at Roger Heights Elementary School in Bladensburg reads, "People can't treat you badly without your consent." Dudley said it's a reminder to her students to stand up for themselves and demand respect.

Dudley, a longtime Democrat and community activist, said she took that sign to heart when she decided to join the Green Party and challenge six-term incumbent Rep. Albert R. Wynn (D-Md.) for the 4th Congressional District seat. She is frustrated with what she said is Wynn's considerable influence in Prince George's County politics, especially in the selection and endorsement of candidates.

This fall, for example, Wynn supplied Will Campos, an aide to County Executive Jack B. Johnson (D) and a political newcomer, with the manpower, money and campaign manager that helped him win the Democratic nomination to fill a vacancy on the County Council.

"I didn't elect him to be Mr. Kingmaker," Dudley, 41, said of Wynn. "He wasn't elected to select our elected local officials. He was elected to represent us, and he's not doing it. . . . We need to stop the abuse of power that the kingmaker has made in Prince George's County."

Also running is John McKinnis, 30, a Republican who owns an information technology business.

Wynn, in a recent interview, said his involvement is about getting things done in the community. None of his constituents, he said, has complained about where and how he chooses to intervene.

"That's primarily an argument for wannabe politicians," Wynn, 53, said.

Dudley has substantive differences with Wynn. She doesn't want casino gambling at National Harbor, the planned development on the Potomac River at Oxon Hill. Wynn has pushed hard for it. She also questions Wynn's decision to break with the majority of the Congressional Black Caucus by voting to authorize the war in Iraq. Wynn said he now regrets the vote.

"We need a national policy that is going to promote peace," Dudley said. "Not this, 'You hit me, I'll hit you back,' or 'You look like you're going to hit me. I'm going to bomb you.' "

Though she criticizes Wynn for meddling in local affairs, the other issues she mentions in her campaign, such as reducing crime and cutting class sizes in crowded schools, are decidedly local.

There is also an unmistakable element of personal pique surrounding Dudley's challenge of Wynn. Three times, she sought, unsuccessfully, Wynn's endorsement in primary races for the Prince George's County Council. And three times she lost the election. Rather than run against one of Wynn's anointed candidates, Dudley decided to take the fight right to him.

"I just feel like we've been consenting to this too long," Dudley said of Wynn's involvement in county issues. "Until somebody stands up to him, he's going to keep on doing it."

She said she is undaunted by Wynn's half-million-dollar coffer or the 87 percent of the vote he took in the 2002 election. Dudley has raised just a couple thousand dollars, she said.

"She's a hard campaigner," said council member David Harrington (D-Bladensburg), a Wynn endorsee who defeated Dudley in 2002. "And she's consistent with her message. . . . But it's one thing to have a message, and it's another to have the resources to show the voters there's a choice out there.

"She's a fighter. Whether you like her or not, or even agree with her or not, you have to admire that about her."

After losing to Harrington in the primary, Dudley backed Jason Fenwick, Harrington's Republican opponent.

The move, some say, hurt the former Democrat politically. But she says: "The Democratic Party has been taking African American votes for granted."

It's a safe bet that this election won't help her relationship with Wynn.

When Dudley entered the race, she said that were it not for copyright infringement laws, her campaign slogan would have been: "Watch out, Fat Albert: Here comes Dudley Do-Right."

"It just resonates doesn't it?" Dudley said. "He's become a fat cat, taking money from special-interest groups. It's time to do the right thing."

Dudley began her pursuit of a council seat in 1994, three years after moving with her husband to Landover from Springfield, Mass.

She summed up the reasons behind her decision to run for office in three words: "I was mad."

Mad about the drug dealers in her neighborhood. Mad that there were no sidewalks for mothers to push their strollers.

Dudley spent more than $10,000 of her savings in her past three races. "It was over 10 years, but that's still a lot of money," she said.

Her biggest fight was against the late Washington Redskins owner Jack Kent Cooke and his plan to build a football stadium in her community. She lost that David vs. Goliath fight, too.

Dudley said she'll be at school Wednesday. She has a bylaws committee meeting with her teachers union. "If I don't win, I'll show my students how to be gracious in defeat," she said.

"I won't be a loser because I'm at least trying."

Theresa Dudley makes her case to Kelly Hanlon of Euclid Park as Dudley seeks to upset a powerful incumbent in Congress.Theresa Dudley, right, a Green Party candidate for Congress, talks with Tracy Hartmann after putting a sign in Hartmann's yard along Cheverly Avenue.