Winning the governor's mansion in 2018 is a long shot for any Texas Democrat.

Gov. Greg Abbott is the comparatively popular leader of a Republican Party that hasn't lost a statewide election in almost a quarter century. And he has amassed a staggering $43 million campaign fund, almost enough to mail every registered voter in the state a check for three dollars.

ENDORSEMENTS: See who the Houston Chronicle editorial board supports in the primaries

Nonetheless, Democratic voters casting their ballots in next month's primary will choose between nine candidates for governor. Most of them have no chance of winning, but they're running anyway for the simple and admirable reason that they believe somebody has to offer Texans an alternative to the state's cynical current leadership.

Democrats need to choose the candidate who, quite simply, will appeal to the most voters in a contest against Abbott. We believe that candidate is Andrew White.

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White, 45, is a Houston entrepreneur who's never before run for office, but he's not exactly a political novice. He's basically the Democratic George W. Bush of this race. Like Bush in 1994, he's never won an election. And like Bush, his most valuable political asset is his father's name. He's the son of former Gov. Mark White, an education reformer who was respected by many Texas Democrats until the day he died last August.

White has cast himself as a common sense Democrat running for governor "to bring sanity and reason back to state government." His top priority is improving public education, and he's campaigning on a pledge to give every public school teacher a $5,000 a year raise. White proposes to fund his teacher pay hike by closing loopholes under which big businesses routinely dodge paying billions of dollars in commercial property taxes.

We're not exactly fans of political dynasties, but White ultimately won our endorsement with his answer to one obvious question. He's the only Democratic gubernatorial candidate who seems to have given serious thought to the state government's role in protecting Gulf Coast residents from flooding. While the other candidates who spoke to our editorial board offered only vague thoughts about this critical issue, White specifically discussed the need for a third reservoir in west Harris County and the importance of leveraging federal funds to build a coastal barrier system.

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After Hurricane Harvey, flood control should be the top concern voters in the Houston area consider when they cast their ballots. Maybe White has a grasp of the issue only because he lives here and he piloted his boat around inundated neighborhoods rescuing flood victims. But any serious candidate for governor speaking to people in Houston should have good answers for basic questions about this topic.

Here's how seriously we take flooding issues. If not for his fuzzy answer to this predictable question, we might have thrown our support to another candidate. Adrian Ocegueda runs a private equity firm in Dallas, and he was an economic policy adviser to the mayor of El Paso. Beyond his views on priorities like education and health care, Ocegueda brings up big issues that aren't on any other candidate's radar. He's concerned Texas isn't doing enough to train workers who are about to lose their jobs as technology displaces human labor. He even has the courage to touch the third rail of Texas politics, suggesting we need to seriously discuss introducing a state income tax. Ocegueda is a conspicuously smart and impressive candidate who has little or no chance of becoming governor, but he deserves serious consideration if he decides to run for another office.

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Lupe Valdez, the former sheriff of Dallas County, is arguably the most high profile contender in this primary, but she also stumbled over flooding questions. Also on the ballot are Jeffrey Payne, a Dallas business owner; Joe Mumbach, a Houston audio-video technician making his first run for public office; and Grady Yarbrough, a retired educator and perennial candidate for statewide office. Three other candidates - Tom Wakely, James Jolly Clark and Cedric Davis Sr. - did not appear before our editorial board.

Next month, Democrats must pick a standard bearer with the best chance of winning votes not only for him or herself, but also for candidates running in down-ballot races. They would be wise to choose Andrew White as their nominee for Texas governor.