Whether it was his vote against the health care legislation or his strategy to sidestep the state’s black political leadership, the decisive defeat of Artur Davis in his quest to become the first black governor of Alabama illustrates the limits of trying to replicate the strategy that helped carry President Obama to office.

Ron Sparks, the Alabama agriculture commissioner, seized a 24-point victory over Mr. Davis, a four-term congressman, in the Democratic primary for Alabama governor on Tuesday. Even Mr. Sparks was stunned by his winning margin, considering he was on the verge of leaving the race a few months ago to avoid an embarrassing loss.

“We worked hard, we fussed hard, we cried hard,” Mr. Sparks told his supporters who gathered in Montgomery. “Thank you for allowing me to be in the position I’m in.”

While Mr. Davis always had a challenging path to winning a general election for governor in Alabama, where 47 years ago George Wallace stood in the state capitol and proclaimed “segregation forever,” it was his failure to win over black voters that cost him the Democratic primary on Tuesday. He and the state’s four major black political groups have been at odds for years, and his strategy of bypassing the organizations failed.

“The black establishment, the iconic leaders from the civil rights era and the traditional black organizations, ironically and successfully deprived Artur Davis of the nomination,” said Glen Browder, a former Democratic congressman from Alabama. “But they felt he had shunned his own race and he could not win the general election.”

The unofficial vote count on Wednesday showed that Mr. Sparks defeated Mr. Davis 62 percent to 28 percent.

The voters of Alabama joined those in Mississippi and New Mexico in selecting their party’s nominees for House and Senate races who will compete in the midterm elections in November.

In New Mexico, immigration was a dominating issue in the race to succeed Gov. Bill Richardson, a Democrat, who has held the seat for eight years.

Susana Martinez, a county prosecutor who prevailed in a five-way Republican primary, was endorsed by Sarah Palin and supports the new Arizona law allowing the police to check the documents of anyone they suspect of being in the country illegally. Ms. Martinez’s Democratic opponent, Diane Denish, the lieutenant governor, opposes the measure, setting the stage for a fierce debate over the next five months.

The Democratic primary for governor in Alabama delivered the biggest upset, with Mr. Davis, 42, campaigning on bringing change to politics in his state by building a coalition of white and black voters — reminiscent of the strategy employed two years ago by Mr. Obama. Mr. Davis sought to play down race as a factor in the campaign and also worked to show his independence from Mr. Obama, including opposing the health care law earlier this year.

“This is not exactly the speech I’d planned to give tonight,” Mr. Davis told crestfallen supporters in downtown Birmingham. He added, “We need to fix things in Alabama and we need to go forward, and I urge you to get behind Sparks to make that happen.”

A variety of polls showed him with a 10-point lead in the race. His advisers attributed the defeat, in part, to low turnout among rank-and-file voters. But the 24-point loss signaled that his argument had fallen flat with Democrats and that he had failed to create a sense of enthusiasm among black voters, who make up close to 60 percent of the primary electorate.

Mr. Sparks campaigned aggressively for the endorsements of the state’s four major black political organizations and sharply criticized Mr. Davis’ vote against health care legislation earlier this year.

Mr. Browder, the former Alabama congressman who studies the politics of race in the state, said the victory by Mr. Sparks showed that the traditional black power structure that Mr. Davis tried to go around still carried significant weight in primary elections.

“Some may find this surprising and disturbing, but this is the way that blacks have maximized their influence in the South for decades,” Mr. Browder said, “and it looks like they will continue to control and channel black influence in the political process.”

Seven Republicans sought their party’s nomination for governor in a race that featured a heated debate over immigration and expanding gambling in the state, but none emerged with more than 50 percent of the votes. With 99 percent of precincts reporting, Bradley Byrne had 28 percent of the vote, followed by Robert Bentley at 25 percent and Tim James at 25 percent. A runoff election on July 13 will decide the nomination.

A sitting Republican congressman, Parker Griffith, lost his primary challenge in Alabama. Last year, Mr. Griffith left the Democratic Party to become a Republican, hoping to improve his chances of winning re-election. But he fell short in a rematch with Mo Brooks, a county commissioner Mr. Griffith narrowly defeated two years ago when he was a Democrat.

The National Republican Congressional Committee followed its policy of supporting incumbents and backed Mr. Griffith, even though he had been a Republican for only five months. With nearly all precincts reporting, Mr. Brooks led Mr. Griffith 51 percent to 34 percent.

Senator Richard C. Shelby of Alabama easily prevailed in his Republican primary challenge from a Tea Party activist. Mr. Shelby, a four-term senator, was first elected as a Democrat in 1986, but changed parties in 1994 after Republicans won control of Congress. He is heavily favored in November against William Barnes of Birmingham, who was leading in the Democratic primary on Tuesday night.

Democrats also were watching to see which Republican would win the nomination to run against Representative Bobby Bright in the Montgomery-centered Second Congressional District. A city councilwoman, Martha Roby, was the Republican establishment pick, and the Tea Party candidate was a former Marine, Rick Barber, a political novice.

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