If the opinion polls are right — Sarah Palin notwithstanding — Republican Rob Maness will exit the stage in the U.S. Senate campaign after the general election Tuesday.

But he has run a vigorous and attention-getting race that has attracted considerable support — enough to prevent either of the two front-runners, Democratic incumbent Mary Landrieu and Republican U.S. Rep. Bill Cassidy, of Baton Rouge, from getting the majority of the vote needed for outright victory, according to opinion polls. Landrieu and Cassidy appear headed for a Dec. 6 runoff.

A retired Air Force colonel making his first try for elective office, Maness registered at 15 percent of the Tuesday vote in two polls released over the weekend — still about 20 percentage points behind Cassidy and about 30 behind Landrieu. But that represented his high-water mark in the campaign to date, according to the compilation on the Real Clear Politics website.

“Anything Rob Maness gets over 10 percent of the vote is going to be a victory for him,” Pearson Cross, who teaches political science at the University of Louisiana at Lafayette, said earlier this fall.

Cassidy has the backing of the Republican establishment and has raised $11 million to Maness’ $2.6 million. The national Republican Party is betting on Cassidy to defeat Landrieu — the fundraising leader, at $16.8 million — as a key step toward capturing a Senate majority in the fall elections.

Although Cassidy is rated more conservative than the average House Republican, Maness calls himself the only true conservative in the race. A list on his campaign website includes endorsements from three groups with “tea party” in their names, as well as from Palin, the former Republican vice presidential candidate and tea party icon who predicted in a recent fundraising email that Maness “is confounding the ‘experts’ and is going to shock the establishment on Election Day.”

Maness’ performance Tuesday could indicate how successful tea party candidates may be in the future in Louisiana. So, too, could the fate of other tea-party-backed Republicans such as Paul Dietzel and Lenar Whitney in the 6th Congressional District, and Zach Dasher in the 5th Congressional District.

Maness, Dietzel, Whitney and Dasher can claim the tea party mantle by virtue of endorsements or contributions from groups that explicitly declare their tea party affiliation. But, as the differing endorsements in the 6th District show, the label is essentially subjective: There is no official tea party national committee and no orthodox party organization, and none of the 535 members of Congress lists “tea party” as his or her partisan designation.

What makes up the tea party platform also is subject to debate. Resistance to big government and taxation stand out as unifying principles, along with a desire to reduce the federal deficit. But there’s ambiguity about whether the rubric comprises the conservative positions on such social issues as abortion, same-sex marriage and legalization of marijuana.

Louisiana has its own flavor of tea party, said Bob Reid, head of the Tea Party of Louisiana, whose 15,000 signed-up members make it the state’s largest tea party organization.

“The independent tea parties, like us, but not necessarily the national tea parties, are very closely aligned with the evangelical community because they are strong Christians,” Reid said.

Woody Jenkins, a former state representative from East Baton Rouge Parish who chairs the parish Republican Party (and who narrowly lost to Landrieu in the 1996 Senate election), also said the Louisiana version of the tea party leans Christian.

“The tea party, as such, is not a large organization in Louisiana,” said Jenkins, who has endorsed Maness. “It’s more a loose association of people who share similar philosophies. And to some extent, there’s a large overlap of people who are also in the evangelical movement.”

The tea party movement emerged in the second half of the century’s first decade, given an impetus by the iconoclastic presidential candidacies of former U.S. Rep. Ron Paul, R-Texas and father of U.S. Sen. Rand Paul, of Kentucky, who has been called its “intellectual godfather.” Its name refers to the Boston Tea Party, when Massachusetts patriots dumped tea in Boston harbor to protest imposition of a tax on tea by the British government before the American Revolution.

The movement may have crested in 2010, when several tea-party-affiliated candidates — all Republicans — won election to Congress, including Jeff Landry, of New Iberia, in the 3rd Congressional District in southwest Louisiana. But in both that year and in 2012, ultraconservative candidates defeated more mainstream Republican candidates in Senate primaries only to lose winnable general elections to Democrats (also in 2012, Landry lost to fellow House member Charles Boustany, of Lafayette, a more mainstream Republican, when redistricting threw them together).

The Senate electoral defeats prompted a backlash from the Republican establishment, which intensified in 2013 when, in a budget dispute with Democratic President Barack Obama, tea party House members forced a federal government shutdown that damaged the Republican brand. So far in 2014, most mainstream Republicans have turned back intraparty tea party challenges (with the notable exception of former House Majority Leader Eric Cantor, defeated in a Virginia primary).

But at the same time, the impact of the movement has put pressure on the Republican Party to recognize the insurgents’ grievances.

“They have, in many ways, successfully caused the Republican Party to give them some public policy lip service to kind of bring them in,” said Joshua Stockley, a professor of political science at the University of Louisiana at Monroe.

Cassidy appeared Saturday at a rally sponsored by the Northshore Tea Party near Abita Springs, sharing the spotlight with national conservative favorite Ben Carson. Carson, a potential Republican presidential candidate in 2016, urged the crowd to vote for Cassidy. U.S. Sen. David Vitter and House Majority Whip Steve Scalise, both Louisiana Republicans, also participated in the event.

But Stockley doesn’t see the tea party as a force capable of boosting candidates like Maness to victory.

“The state of the tea party in Louisiana is not unlike the state of the tea party essentially everywhere else in the nation,” he said. “It is a fragmented, disorganized group of ultraconservative individuals. They are not only a minority in the general public; they are a minority in their own party.”

Mark Ballard, of The Advocate Capitol news bureau, contributed to this article. Follow Gregory Roberts on Twitter, @GregRobertsDC. Follow Mark Ballard on Twitter, @MarkBallardCNB. For more coverage of government and politics, follow our Politics Blog at blogs.theadvocate.com/politicsblog.