Updated

What could have been a tight, tea party-fueled primary now looks like a cakewalk for U.S. Sen. John Cornyn after his challenger ran a campaign so disastrous that even top grassroots activists in Texas have disavowed him.

Cornyn, the Senate's No. 2 Republican as minority whip, should have little trouble securing the GOP nomination Tuesday in his bid for a third term, even though some activists dismiss him as too moderate and his firebrand colleague, U.S. Sen. Ted Cruz, has refused to say whether he'll vote for him.

Cornyn appears safe because the best-known of the seven Republicans vying to unseat him is U.S. Rep. Steve Stockman. The congressman stunned political observers when, just three months before the primary, he withdrew his re-election bid to his suburban Houston district and filed to run for Senate.

Famous for outlandish comments in support of gun rights and calls to impeach President Barack Obama, Stockman began his campaign with more debt than cash-on-hand. He also was dogged by accusations of ethics violations -- only to see things get worse. He attended almost no major campaign events. And he even dropped out of sight for weeks in January, ignoring reporters and missing almost 20 votes in the House before explaining he had been part of an official overseas delegation at least part of that time.

Last week, leading conservatives suggested in an open letter to Stockman that he ran "the laziest statewide campaign to date" and added: "There is nothing about your conduct that represents the spirit of grassroots conservatives in the Texas tea party."

Meanwhile, five Democrats also are vying for the seat -- though no Democrat has won statewide office in Texas since 1994.

One of the hopefuls, activist Kesha Rogers, is a conspiracy theorist who wants to impeach Obama and who the party says isn't a real Democrat. Democratic Party Chairman Gilberto Hinojosa even drafted a mass email identifying Rogers as a follower of political extremist Lyndon LaRouche and noting that she wants to colonize Mars.

"Do not vote for Kesha Rogers," Hinojosa warned.

Lebanon-born Dallas dental mogul David Alameel unsuccessfully spent $4.5 million running for Congress from Fort Worth two years ago and has promised that money won't be an object should he win the party's Senate nomination. Alameel, who has been endorsed by Democratic gubernatorial hopeful Wendy Davis, traveled to Afghanistan in 2000 to negotiate with the Taliban about the possible handover of Osama bin Laden to U.S. authorities -- but those talks stalled after the Sept. 11 attacks.

Alameel has been criticized by rival Maxey Scheer, an El Paso personal injury attorney who notes that Alameel has given millions of dollars over the years to both political parties -- including top Republicans in Texas and nationally. Scheer claims Cornyn has allowed Texas to operate on "Cruz control," dominated by the state's junior senator.

The final pair of Democrats on Tuesday's ballot are Houston attorney and businessman Michael Fjetland and Odessa-based family physician Harry Kim.