Editor's note: This story has been updated throughout.
They topped the field with 78 percent of precincts reporting early Wednesday, earning enough support to face off in May for an open seat on the commission that oversees the state’s iconic oil and gas sector.
Gates drew 29 percent of those votes. Christian, of Center, had registered 20 percent in a seven-way race that looked destined for a runoff from the start.
Ron Hale, with 15 percent of the votes, was in third.
The top vote-getter in the runoff will face the winner of the Democratic primary, where Grady Yarbrough and Cody Garrett advanced to a runoff.
The men are looking to fill David Porter’s shoes on the three-member commission, which also regulates mining, pipeline safety and natural gas utilities, but not railroads. Porter, who was first elected in 2010, shook up the Texas energy world in December when he announced that he would not seek re-election. That triggered a host of last-minute campaign launches.
That included another Christian — Railroad Commission geologist Lance Christian, who ran solely on his scientific expertise. He sat in fourth place late Tuesday at 12 percent.
The contests have unfolded as an epic crash in oil prices has plunged the petroleum industry into a world of uncertainty — spurring bankruptcies, layoffs and talk among candidates about how the commission should respond.
For the most part, the Republicans have stuck to the party’s bread-and-butter talking points, speaking of fighting back against the federal Environmental Protection Agency and maintaining a light regulatory touch to protect producers in Texas.
With few concrete differences in policy, the candidates have largely sought to distinguish themselves by citing their backgrounds.
Gates, who previously failed in four Texas Legislature bids, has suggested on the campaign trail that the commission needed someone with his knack for business. He was by far the biggest spender in the race — and the most visible advertiser, shelling out more than $1 million ahead of primary day. As of late February, he had an outstanding $2 million loan.
“This is exciting, when you have this many people, when you have to come from virtually nothing,” he said in an interview Tuesday night, acknowledging that the big spending “certainly gave me the edge.”
Christian, who reported spending roughly $40,000, has suggested that his lengthy career in the Texas House makes him fit for the commission.
The one-time president of the Texas Conservative Coalition was first elected in 1996 and served seven terms until he was unseated in 2012. He was involved in oil and gas issues while serving on energy-related committees.
With the field whittled, the candidates will seek to further distinguish themselves. On Tuesday, Gates revealed one line of attack against Christian, labeling him a “career politician.”
Christian did not immediately return a message early Wednesday morning.
On the Democratic side, Yarbrough, a former U.S. Senate candidate from San Antonio, led with 40 percent of the votes. Garrett, a former Democratic campaign director, finished second with 35 percent.