AUSTIN, Texas (Reuters) - Texas Lieutenant Governor David Dewhurst and Tea Party favorite Ted Cruz were headed to a U.S. Senate election runoff in July after neither secured the more than 50 percent of the vote required to win the Republican primary on Tuesday.
The nine-candidate primary for the seat that Republican Senator Kay Bailey Hutchison is leaving open also included former Dallas Mayor Tom Leppert. The Republican primary is key because Texas has not elected a Democrat to statewide office since 1994.
Dewhurst led the field, but did not manage to avoid a July 31 runoff. He had about 45 percent of the vote and Cruz about 34 percent with 84 percent of the precincts counted, according to unofficial results on the Texas Secretary of State website.
The election's outcome is not likely to change the party balance in the U.S. Senate, which now has a Democratic majority. But it was watched closely as another battle between the conservative Tea Party movement and more traditional Republicans for supremacy in the Republican Party.
National conservative groups such as Club for Growth and the Senate Conservatives Fund poured money into Cruz's campaign, emboldened by wins from insurgent conservatives against traditional Republicans in Senate primaries elsewhere in the country. In Indiana, a candidate backed by the Tea Party beat longtime U.S. Senator Richard Lugar, and in Nebraska, first-time statewide candidate Deb Fischer beat a veteran attorney general.
James Henson, director of the Texas Politics Project at the University of Texas, said the important question is who will be motivated to show up for a runoff in July.
"That is almost certainly going to be the more ideological voters, it's going to be more conservative voters," Henson said. "While Cruz poses a real challenge to Dewhurst on that front, they are competing over those voters and splitting them relatively evenly."
Cruz does not get the support of all Tea Party activists, who want to dramatically cut U.S. government spending and want to elect conservatives who will be assertive in Washington.
Brendan Steinhauser of the conservative group FreedomWorks, which backs Cruz, said those activists would get behind Cruz in the runoff.
"They are all united when it comes to the belief that David Dewhurst does not represent their values," he said.
The Texas race became a battle over who was the most conservative, with Republican Governor Rick Perry backing Dewhurst and former vice presidential nominee Sarah Palin endorsing Cruz.
"Now, more than ever, we must work to send a proven conservative leader like David Dewhurst to Washington, where he can put the Texas approach to work to overhaul Washington," Perry said in a statement on Tuesday.
Dewhurst was the front-runner in the race. He loaned his campaign $9.2 million, his campaign said last week.
A businessman and a former state land commissioner who has served in the U.S. Air Force and with the CIA, Dewhurst has presided over the Texas Senate since 2003.
Cruz, a Houston lawyer and former state solicitor general whose father came to Texas from Cuba, criticized Dewhurst for compromising with Democrats in the state Senate. Club for Growth says it spent $2.5 million, plus bundled more than $750,000 directly for members, in support of Cruz.
In the Democratic primary to choose an opponent for Dewhurst or Cruz in the Senate race, former state Representative Paul Sadler was leading although he also did not get more than 50 percent and will be forced into a runoff in July.
Texas added four U.S. House of Representatives seats because of its population growth in the 2010 census, mainly because of a rise in the number of Hispanics. But the redistricting map drawn by majority Republicans in the state may limit Hispanic gains in the Texas congressional delegation.
One Hispanic incumbent, Democratic U.S. Representative Silvestre Reyes, seeking a ninth term in Congress, was losing in the Democratic primary to challenger Beto O'Rourke, a former member of the El Paso City Council.
Additional reporting by Alexander Cohen, Alina Selyukh, Nick Carey and Marice Richter; Editing by Greg McCune and Eric Beech