Despite spending $5 million of his own fortune on his campaign, Dewhurst has struggled to gain ground on state Sen. Dan Patrick. A victory by Patrick, a fiery conservative talk radio host and founder of the Legislature's tea party caucus, would complete the overhaul of every elected statewide office next year when Gov. Rick Perry steps aside.
Republican nominations for four major offices -- including attorney general and agriculture commissioner -- and nearly a dozen statehouse seats will be settled after crowded primary battles in March resulted in a busy slate of runoffs.
With Texas Democrats again underdogs in November, many tea party-aligned candidates favored to win Tuesday would be poised to pursue an aggressively conservative agenda that would likely include further spending cuts, expanded gun rights and more restrictions on abortion.
"We're supposed to be this very conservative state, and the people in Texas are, yet our Legislature doesn't always reflect that," said Republican Konnie Burton, a tea party leader from Fort Worth who is running for Davis' state Senate seat. "We are going in a different direction than many states, but I don't think we're the only ones. We're probably just louder. We're Texans, right?"
For Democrats, it's a less lively runoff. Voters from that party's main decision is choosing a U.S. Senate nominee to serve as token opposition to powerful Republican incumbent John Cornyn, and Democrats have spent much of the primary trying to dissuade their supporters from picking Kesha Rogers, who has called for impeaching President Barack Obama yet still forced a runoff against David Alameel of Dallas, who made millions with a chain of dental clinics.
Most attention and money, however, has been directed at the Republican races.
Dewhurst, who finished a distant second in March, has reached into his own pocket, trying to mount a comeback and shed accusations he's become too entrenched and moderate after 11 years in office. But Patrick has seemingly attracted more support -- a $4 million haul of donations in the last two months -- impressive even by Texas' lofty political fundraising standards.
Candidates have wooed GOP voters by saying Texas can do more to expand gun rights, further restrict access to abortion and increase police presence on the Texas-Mexico border to slow the flow of immigrants in the United States illegally. Some top conservatives also want to expand the powers of state and local police to check the immigration status of people they encounter.
Tea party-backed candidates have also admonished the Republican-controlled Legislature as being financially reckless while vowing to slash economic incentives they deride as corporate welfare.
That troubles Bill Hammond, a Republican and president of the influential Texas Association of Business, who said he is worried about Texas losing a competitive edge in luring companies and about the GOP turning away Hispanic voters.
"It's much more so this cycle than you have in the past. You've seen some very solid conservative candidates defeated in the Texas Republican primary, unfortunately," Hammond said. "It's absolutely a concern more and more for us."
Unlike in 2010 and 2012, tea party-backed candidates in Texas and elsewhere are dealing with a disappointing election year, particularly in congressional and U.S. Senate races. But when it comes to statewide races, many candidate are trying to emulate Ted Cruz, a once little-known state solicitor general who upset Dewhurst for the 2012 U.S. Senate nomination.
Cruz rode a wave of grassroots support to Washington and later bolstered Burton's campaign with a rare endorsement. He said during a recent visit to Austin that his home state stands out with March's primary results.
"I think Texans want principled leaders who will listen to the people," Cruz said.
Even a GOP runoff for a seat on the State Board of Education has shades of tea party-versus-establishment. Pat Hardy, a 12-year incumbent on the solidly conservative board that has gained national attention over ideological battles over creationism and magnifying Christianity in history lessons, faces a challenge from Eric Mahroum that puzzles even her critics.
"She was a Texas Republican before being a Texas Republican was cool," Dan Quinn of the Texas Freedom Network, a liberal-leaning watchdog, said of Hardy, from Weatherford, outside Fort Worth. "She's been pretty darn conservative. It's sort of remarkable that's where the division is these days."