The Texas Republican Senate primary will go to a runoff, the AP projected on Tuesday night, with Lieutenant Governor David Dewhurst and former Solicitor General and tea party up-and-comer Ted Cruz facing off in the contest, which is scheduled for July 31st.

In order to win their party's nomination outright, a candidate in Texas must receive at least 50 percent of the vote. With roughly 61 percent of precincts reporting, Dewhurst had 46 percent. Cruz had 33 percent. Former Dallas Mayor Tom Leppert and former ESPN analyst Craig James were in a distant third and fourth place, with roughly 13 percent and 4 percent of the vote, respectively.

Cruz has had argued that he will be the beneficiary in a runoff.

"If we get to a runoff, we win decisively," Cruz told ABC News in an interview.

Dewhurst said his strategy in a runoff will be the same as his strategy in the primary - to be the top vote-getter.

"As long as I do that then we'll either win the primary on Tuesday night or we'll win the primary on the runoff date on July 31? he said.

Many GOP strategists in the state believe that Cruz will do well in a runoff, as turnout is likely to drop off to a more conservative bloc of voters, who would presumably be inclined to back Cruz. However, Dewhurst could get a bump from Leppert supporters. If they turnout in the primary, conventional wisdom is they would likely favor the Lt. Gov over the former Solicitor General.

The Dewhurst/Cruz battle has largely been framed as a tea party vs. establishment fight - a narrative driven in part by Cruz himself, who has framed himself as an outsider, and Dewhurst as an establishment moderate. Dewhurst however, has received the backing of several prominent conservatives, including Rick Perry and Mike Huckabee. Cruz has been endorsed by tea party stars like Sarah Palin and Jim DeMint, and has been financially supported by prominent conservative groups like FreedomWorks and Tea Party Express.

Going into the primary, the Senate race was the costliest of the 2012 cycle, with over $25 million spent so far. It is likely that number will continue to rise as the two candidates head into the final slog of their campaigns.

The Democratic primary in Texas will also go to a runoff between former State Representative Paul Sadler and Grady Yarbrough, a San Antonio resident, the AP reports. That primary has received significantly less attention however, as the Senate seat, currently held by retiring Sen. Kay Bailey Hutchison, is widely considered to be safe for Republicans. Democrats have not won a statewide election in Texas since 1994.