The new epoch in American politics is accelerating in Texas and nationally -- the struggle for the growing Hispanic vote. The headliners are Republican Ted Cruz, running for U.S. Senate, and Democrat Julian Castro, mayor of San Antonio. Cruz and Castro are not opposite on the ballot this fall, but don't let that technicality fool you. The race is on between the contrasting futures they represent.Cruz's GOP primary victory over David Dewhurst came the day Castro was selected to give the keynote at this year's Democratic National Convention. It's a big deal that these two new Texas national standard-bearers are both Hispanic. Our nation's Hispanic population grew 43 percent in the last decade; Texas is projected to be majority Hispanic by 2020.Both Castro and Cruz are Harvard-educated lawyers, and their competing speeches in Tampa and Charlotte showed that they're both gifted orators. But they offer astoundingly different visions about the priorities and values of our nation and the role of government in society: Is government an agent of the public good or an enemy of the free market?Cruz speaks of our "stark choice" and the belief that "government is not the answer" but fosters "dependency, destroying individual liberty." He pledges to "restore our constitution" and "return to the founding principles." Cruz sees the greatest steps forward over the last two years not in Republican gains against Democrats, but in Tea Party victories against established Republicans. He favors repealing Roe v. Wade; abolishing the federal Education, Energy and Commerce departments and the IRS; replacing Social Security with private accounts; and blocking nontraditional paths to citizenship.With 65 percent of Texas' Hispanics historically voting Democratic, and similar numbers nationally, can Cruz help make Republican inroads in our fastest-growing voting bloc? Failure to stem this tide may mean an inevitable "blue" shift in Texas. The choice of Castro to fill the same convention slot that launched Obama into the White House should be lost on no one. Castro speaks with a very different voice from Cruz: "The path is always forward," and, as individuals, we "recognize there are some things we cannot do alone."Castro is pro-choice and supports expanding college loans, providing healthcare for all, boosting preschool programs for children and enacting the Dream Act for immigrants. He sees government-built roads, schools and infrastructure as creating "opportunity today, prosperity tomorrow" and envisions government not giving handouts but assuring a chance for each American to succeed.Castro rejects the notion that "if we all just go our own way, our nation will be stronger for it," saying instead that "if we sever the threads that connect us, the only people who will go far are those who are already ahead."The narrative of what drew Castro to become a Democrat and what caused Cruz to become a Republican -- and which better attracts Hispanic and crossover voters -- probably will decide who leads Texas, and likely the nation, over the coming decades.Castro surely agrees with Cruz that voters have a "stark choice"-- between a view that government fosters dependency and a view that government can foster prosperity. Giving people a clear choice is what a political campaign should be about.Former state Rep. Jim Dunnam was House Democratic Leader and chaired the House Committee on Federal Economic Stabilization Funding. He is a senior fellow at the Texas First Foundation, a nonprofit, nonpartisan group that focuses on state policy. www.jimdunnam.com.