By Molly Hennessy-Fiske, Los Angeles Times

HOUSTON — Republican incumbents threatened by tea party challengers emerged triumphant in Tuesday’s Texas primary, with longtime U.S. Senator John Cornyn and U.S. Rep. Pete Sessions coasting to victory.

The primary also marked the electoral debut of the fourth generation of the Bush dynasty with George P. Bush’s candidacy. The son of former Florida Gov. Jeb Bush, nephew and grandson of the former presidents and great-grandson of a U.S. senator, the 37-year-old won the Republican nomination for Texas land commissioner, a little-known but powerful post that has served as a launching pad for state politics.

The Associated Press projected all three as the winners shortly after polls closed.

The Texas election kicked off the 2014 campaign season with themes expected to play out among conservatives across the country this year. Cornyn was one of more than a dozen incumbent GOP senators facing tea party opponents, and Bush is among several candidates trying to parlay family ties into elective office.

Cornyn, the Senate’s second-ranking Republican, led in early returns Tuesday over U.S. Rep. Steve Stockman, who represents a district to the south and east of Houston. Stockman waged a bizarre campaign, skipping public appearances and relying on gags such as rewarding donors with Obama barf bags. The victory makes Cornyn the odds-on favorite in November; Democrats have not won statewide office in Texas in 20 years.

Some experts consider Cornyn’s margin of victory, once all the ballots are counted, a bellwether of anti-incumbent sentiment.

“If Cornyn comes out below 60 percent, then the sense is that he looks relatively weak,” said Jim Henson, who directs the Texas Politics Project at the University of Texas at Austin. As early votes were counted, Cornyn was exceeding that level.

“It’s a protest vote,” said Stuart Rothenberg, who analyzes races for his nonpartisan Rothenberg Political Report, adding that if Stockman were to get 20 percent to 25 percent of the vote, “it would tell you there’s a chunk of the Republican Party who will vote for anybody who challenges the Republican establishment.”

Mark Jones, chairman of the political science department at Houston’s Rice University, was tracking Cornyn’s margin of victory compared with that of Republican gubernatorial nominee Greg Abbott.

Abbott, the state attorney general, had far more cash and name recognition than his three challengers and had already been facing off against the Democratic candidate for November, state Sen. Wendy Davis. Davis garnered national attention last year during her 11-hour filibuster of state legislation that eventually restricted access to abortion statewide.

“The closer Cornyn is to Abbott, the better we should gauge his performance,” Jones said.

In the governor’s race, the first without an incumbent since 1990, voters can expect continued “trench warfare” between Abbott and Davis on a statewide and national scale, Henson said.

The two have been attacking each other in recent months over everything from his alliance with shock rocker Ted Nugent to exaggerations in the onetime single mother’s hard-luck campaign trail biography.

“We’ll continue to see them battling it out from news cycle to news cycle,” Henson said.

Like Cornyn, Sessions beat back a tea party challenge, his by activist Katrina Pierson.

Bush’s primary opponent, east Texas businessman David Watts, raised a fraction of the millions Bush amassed. It’s been nearly five years since a Bush held elected office, the longest lapse in 32 years. Partisans hope that Bush, a Fort Worth lawyer and Navy veteran fluent in Spanish, will revive his family’s role in Republican politics while expanding the party’s appeal to Latino voters.

“Republicans around the country who remain loyal to former President George W. Bush and his father are going to see this George Bush as part of that legacy and somebody they can support. And other Republicans are going to see George P. as quite a profile: His mother’s Mexican, he can appeal to Latino voters, he’s young, articulate,” Rothenberg said. “The question is what kind of resume does he build in office.”

Photo: Gage Skidmore via Flickr