Kay Bailey Hutchison's decision not to seek re-election created an all-too-rare situation -- an open U.S. Senate seat representing Texas.Republican primaryThree heavyweights top a Republican card of nine candidates. On the issues, they are difficult to distinguish: Repeal "Obamacare," rein in government spending, support the military, secure U.S. borders, define marriage as between one man and one woman.Texans are more than passing familiar with Lt. Gov. David Dewhurst, 66, who has served in statewide offices since 1998. But voters are justified in asking if Dewhurst's drift to more dogmatic conservative positions is a result of deep reflection and an assessment of what's best for the state or is purely a result of his wanting to become a U.S. senator.The Houston businessman has had aspirations of higher office since his days as Texas Land Commissioner. Political observers weren't sure whether he would go for governor or the Senate. He picked the office that came open first.Former state Solicitor General Ted Cruz, 41, is the undeniable Tea Party candidate in this race.As a former debate champ from his school days, there's no question he would make impassioned floor speeches if he ever gets to Washington as an elected official.But the Houston attorney was more on the periphery than at the head table of the successes he claims in federal cases to defend the Constitution and protect U.S. sovereignty. Texas Attorney General Greg Abbott deserves the credit for directing those legal victories.Former Dallas Mayor Tom Leppert, 57, is an intelligent, hardworking leader who has experienced success in both the public and private sectors.After leading major national and international companies, Leppert demonstrated that his ability to negotiate in the boardroom translated well to council chambers, where he was successful in bringing together a previously dysfunctional City Council.That happened by listening to all the stakeholder groups in the city and working on a solution that was best for the community as a whole.That feat impresses folks on this side of the Trinity River because we watched the sideshow that was the Dallas City Council for a long time.Texans need visionary, principled and independent thinkers to represent them in Washington. If Republicans are looking for a new approach to politics-as-usual in the Capitol, Leppert is their answer.The Star-Telegram Editorial Board recommends Tom Leppert in the Republican primary for the U.S. Senate.Democratic primaryThe standout candidate among the four Democrats seeking their party's nomination is former state Rep. Paul Sadler, 56, of Henderson.Sadler, a Rusk County attorney and director of a wind energy advocacy group, served in the Texas House from 1991 to 2003. As chairman of the Public Education Committee in 1995, he worked with Republican Gov. George W. Bush and Democratic Lt. Gov. Bob Bullock to reform the state's education code with the sweeping 843-page law known as Senate Bill 1.Sadler's experience as an across-the-aisle problem-solver on tough issues places him in a category beyond his three opponents.Sean Hubbard, 31, of Dallas previously worked in sales and billing for a small business and coordinated outreach efforts for Obama Dallas in 2008.Grady Yarbrough, 75, a retired San Antonio teacher, ran unsuccessfully for state treasurer and land commissioner in the 1980s and '90s.Addie Dainell Allen, 60, of Beaumont is a federal disaster assistance worker. Her campaign website hasn't been updated since she announced for office Jan. 12.The Star-Telegram Editorial Board recommends Paul Sadler in the Democratic primary for the U.S. Senate.