But Taj Clayton, a DeSoto lawyer, and State Representative Barbara Mallory Caraway of Dallas are giving it a try, arguing that it is time for Ms. Johnson to pass the baton in southern Dallas County’s District 30. The challengers have gotten help. The Campaign for Primary Accountability, a bipartisan “super PAC,” is targeting longtime incumbents — including Ms. Johnson — in Congressional races across the nation. Still, Ms. Johnson has her own big-time booster: President Obama, who generally stays out of such battles, has endorsed her. While she acknowledged that she has not had much primary opposition in her Congressional career, she said she has had general election opponents and does not feel threatened. “I’ve never had a need for telling people what I’ve done,” she said. “They see I’m responsive to the people. It’s pretty visible.” Mr. Clayton, a Harvard-educated lawyer with an ad campaign so polished it has made its own headlines, has his own connections to the president. His chief campaign consultant was Mr. Obama’s 2008 national field director. And Mr. Clayton has a compelling story: he is the grandson of Virginia sharecroppers and the son of Waxahachie factory workers. He worked his way through Harvard cleaning dormitory bathrooms and sweeping staircases. Mr. Clayton, who served on Mr. Obama’s Texas finance committee in 2008, said he knows how allegiances work in Congress, and he is not deterred by the president’s support of Ms. Johnson. “There have been some naysayers, those who said, ‘You aren’t going to be able to raise any money, she has everything sewn up, she’s been there forever,’ ” Mr. Clayton said. “My position was always, I feel called to do this. You’ve got to put the people first, want to see people in our district do better.” Ms. Caraway has been unable to raise campaign money the way that Ms. Johnson and Mr. Clayton have. As of the April 15 primary filing deadline, she had $1,560 cash on hand, compared with Ms. Johnson’s $362,000 and Mr. Clayton’s $158,000. But she is an aggressive block walker and a well-known commodity in the district. She was a Democratic precinct chairwoman before serving on the Dallas City Council for eight years, and she has been in the Legislature since 2007. Her husband, Dwaine Caraway, serves on the Dallas City Council and briefly served as the mayor — though their relationship made headlines last year after he called the police in the midst of a domestic disturbance in which Ms. Caraway reportedly wielded a knife. Many thought it might keep her from challenging Ms. Johnson; it did not. “Even if I had a million dollars, my strategy would not change: I’m getting out every day and knocking on doors, meeting as many people as I can,” Ms. Caraway said. “If you check my prior history with elected office, I’ve always had a ground offensive, a grass-roots campaign. I’ve never been an establishment candidate.” In Congressional District 30, the Democratic primary battle is the big one. Whoever wins will face a Republican and a Libertarian in the general election, but the district votes overwhelmingly Democratic. Dallas political observers think Ms. Johnson is the obvious favorite. Renee Hartley, a Democratic political consultant, said that although Mr. Clayton is wildly charismatic and a great candidate, “I just don’t know that he’s going to be able to get his message as far and as wide and cut into what probably will be for her an overwhelming lead.” No amount of determination or shoe leather will do it for Ms. Caraway either, Ms. Hartley said. Calvin C. Jillson, a political science professor at Southern Methodist University, predicts that Ms. Johnson will win north of 70 percent of the primary vote, but he added that Mr. Clayton — who “has raised a surprising amount of money” — and Ms. Caraway probably expect that and are priming themselves for future campaigns. “Eddie Bernice Johnson is what, 76 at this point?” Dr. Jillson said. “So people are thinking ahead rather than thinking they can beat her directly.”
