Cruz used advantages in nearly all the state's heavily populated counties to secure the party's nod to succeed retiring Sen. Kay Bailey Hutchison. He'll meet Democratic former state Rep. Paul Sadler in November.

The Republican runoff, which gained national attention, was among several Tuesday in Texas pitting mainline Republicans against tea party-backed candidates.

Dewhurst had offered his 14 years of state government experience against Cruz, a former Texas solicitor general running in his first election. Dewhurst counted Gov. Rick Perry among his backers and topped Cruz by 10 percentage points in the May primary but fell short of the 50 percent of the vote he needed to avoid the runoff.

National conservative groups, including FreedomWorks and the Club for Growth, spent millions to help Cruz match Dewhurst's personal fortune and tighten the race.

Dewhurst has overseen the Texas Senate as lieutenant governor since 2003, but Cruz contended Dewhurst was too moderate for sometimes showing a willingness to compromise with Democratic state senators to ensure the flow of legislation.

Cruz also looked to match tea party successes elsewhere this year. Richard Mourdock ousted 36-year Senate veteran Richard Lugar in Indiana, and Deb Fischer in Nebraska defeated two better-known Senate candidates. Cruz drew support from former Alaska Gov. Sarah Palin and South Carolina Sen. Jim DeMint. Dewhurst dismissed the out-of-state backers as outsiders meddling in state politics.

Enthusiasm for the Senate race kept turnout higher than normal for a runoff election that also included races for the U.S. House, the state Legislature, the Texas Supreme Court and other offices. Experts predicted more than 800,000 voters out of about 13 million who were eligible.

"It's my duty, I know I should and I do," retiree Elizabeth Reagen, 93, said outside a Dallas-area precinct. "I'm not always sure that I'm voting for the right person."

She voted for Dewhurst but said she didn't like all the attack ads that marked both sides of the campaign.

"Of course, that's part of it," Reagen said. "But the older I get, the more it bothers me."

Don Steinway, 76, a retired commercial pilot in Houston and tea party advocate, voted for Cruz.

"We're just tired of the government ignoring the Constitution," Steinway said. "I'm tired of these people who promise something for nothing."

Democrats, who haven't won a statewide election in Texas since 1994, picked Sadler, from Henderson in East Texas, over retired San Antonio educator Grady Yarbrough as their choice for U.S. Senate.

Neither raised much money and Yarbrough failed to comply with federal election laws concerning where he had raised money or how he has spent it, according to the Federal Election Commission.

In all, there were 25 Republican and 12 Democratic runoffs, including two Railroad Commission races, one Supreme Court race, three State Board of Education races, eight U.S. House and 17 Texas Legislature races.

Among them were fierce Democratic congressional races in Dallas-Fort Worth and San Antonio.

State Rep. Marc Veasey of Fort Worth had a narrow lead in early votes over longtime Hispanic activist and former state Rep. Domingo Garcia for a new congressional district in the Metroplex, one of four new Texas districts thanks to the state's booming population. Veasey turned out African-American voters in Fort Worth in the May 29 primary and Garcia tried to mobilize his base in Dallas.

In San Antonio, former U.S. Rep. Ciro Rodriguez looked for a chance to regain his seat from Republican Quico Canseco, and was locked in a tight race in early returns with state Rep. Pete Gallego, a rising star in the Democratic Party.

Republicans had similar congressional battles.

Roger Williams, a close ally of Gov. Perry, beat tea party-favorite Wes Riddle in an Austin-area district. Along the Gulf Coast, state Rep. Randy Weber of Pearland defeated Felicia Harris, a Republican party activist, to secure the GOP nomination in the district now represented by retiring Ron Paul.

In far Southeast Texas, financial planner Stephen Takach tried to keep former one-term congressman Steve Stockman from securing the GOP nomination in another new district. The early vote was close.

The outcomes of Texas House and Senate runoffs could make the Legislature a more tumultuous place.

Veteran Republican Sen. Jeff Wentworth of San Antonio lost in his tough runoff campaign against emergency room physician Donna Campbell, a tea party leader making her second bid for office.

In state House races, senior committee chairmen Rep. Sid Miller of Stephenville and Rep. Chuck Hopson of Jacksonville were forced into runoffs as part of anti-incumbent, tea party insurgencies. Miller was losing to family doctor J.D. Sheffield, of Gatesville. Hopson, a former Democrat, was losing to Travis Clardy, an attorney from Nacogdoches.

CLICK HERE FOR FULL RESULTS IN ALL RUNOFF ELECTIONS

Other results from Tuesday's runoff elections

• Texas Railroad Commission Chairman Smitherman wins Republican nomination to retain his seat.
• Texas Railroad Commission Chairman Smitherman wins Republican nomination to retain his seat.
• Craddick defeats Chisum for Republican nomination for seat on Texas Railroad Commission
• Former Texas state lawmaker Sadler beats Yarbrough, wins Democratic nomination for US Senate.
• Devine defeats incumbent Texas Supreme Court Justice Medina for Republican nomination.