It’s a scenario any Hollywood screenwriter could whip up: As the clock ticks down toward the big election, the candidates busily crisscross the state, delivering speeches, shaking hands, hurling attacks at the opposition and tirelessly stumping for every last vote.

Except, in Louisiana this week, that script has applied to only one of the two candidates for the U.S. Senate in Saturday’s runoff election: Mary Landrieu, the incumbent Democrat seeking a fourth term. Her opponent, Republican U.S. Rep. Bill Cassidy, of Baton Rouge, has been missing in action. He not only quit the campaign trail, he left the state altogether, decamping to Washington to attend sessions of Congress.

“He’s ahead,” said political scientist Brian Brox, of Tulane University in New Orleans, offering a laconic explanation for Cassidy’s behavior.

Somewhat more expansively, Joshua Stockley, who teaches political science at the University of Louisiana at Monroe, said, “Rep. Cassidy is way ahead in the polls, and he’s simply minimizing the potential of making a mistake.”

Cassidy’s disappearance has infuriated the Landrieu campaign, which accuses him of going into hiding to avoid potentially embarrassing questions about apparent discrepancies and omissions in the time sheets he’s filled out as a part-time LSU physician since taking his House seat in 2009. Cassidy denies any wrongdoing.

Although Cassidy has said he will return to the campaign in Louisiana on Friday, the Landrieu camp connects his weeklong avoidance of voters and the media to the public revelations of the payroll documents just before Thanksgiving. Cassidy did appear at a Baton Rouge television studio Monday for a broadcast debate with Landrieu, but he left without speaking to reporters.

Landrieu, meanwhile, has been talking up the time-sheet brouhaha this week in campaign stops in Gretna, Hammond and Baton Rouge, in New Roads, Vidalia, Monroe and Grambling, in Minden, Shreveport and Lake Charles.

“Mary Landrieu is behind, and the typical strategy for someone who is behind is to attack,” Brox said. “Whereas the frontrunner — particularly one who appears to be not quite as comfortable on the campaign trail — at this point, with the lead, it seems there’s little he can do to improve his lead.”

But were Cassidy to put his foot wrong, he could weaken his standing, Brox said. “Sometimes just not playing is better than playing,” he said.

“I like the analogy that Rep. Cassidy is simply a quarterback taking a knee and running out the clock,” Stockley said.

The Cassidy campaign said he traveled to Washington to cast votes in the House, including one Thursday for a Republican bill to block Democratic President Barack Obama’s recent executive order to suspend deportations of millions of undocumented immigrants. The bill is largely symbolic — it has no chance of Senate passage before the current Congress adjourns at the end of the year — but it did provide Cassidy with another opportunity to drive home, for the umpteenth time, the overriding message of his campaign: Landrieu supports Obama — whose approval ratings are strikingly low — while he opposes the president.

It’s a message that Republican candidates across the country employed to devastating effect this November in taking eight Senate seats away from the Democrats, so far, to capture a Senate majority in the 2015-16 Congress.

In the open primary in Louisiana on Nov. 4, Landrieu edged Cassidy 42 percent to 41 percent, leaving both short of the majority needed to win outright and sending them to the runoff. But the combined total for Republican candidates on the primary ballot totaled 56 percent, which is close to the level registered by Republican presidential candidates in 2008 and 2012. Opinion polls show Cassidy unifying that Republican majority and heading for an easy win Saturday.

Throughout the long campaign, Cassidy has played his cards close to his vest, spurning invitations to additional TV debates beyond the one Monday and two others before the primary, while Landrieu has pressed for more debates, spoken at dozens of rallies, assisted at a keg stand outside LSU’s Tiger Stadium and joined in a “wobble” line dance at a Southern University tailgating party.

“It was strategy that said, minimize his exposure and minimize his ability to make a mistake,” Stockley said. “Rep. Cassidy — he’s an average politician. He doesn’t have the most charismatic personality. He’s not going to warm up an audience like other politicians we’re used to seeing in the South and in Louisiana.

“He’s not a bad politician; he’s an average politician. His staff recognized that and they made sure his appearances generally were to smaller audiences, selective audiences.

“They minimized access and exposure to him,” Stockley said. “You’re controlling your candidate; you’re controlling your environment. It was a smart strategy. He had some built-in advantages and in many ways, it was, ‘Hey, let’s not screw this up.’ ”

Cassidy’s principal advantage is that his party label is Republican. Landrieu’s last election, in 2008, was the last time a Democrat has won a statewide race in Louisiana. And should she lose, no Democrat from the Deep South states of Louisiana, Mississippi, Alabama, Georgia and South Carolina will serve in the incoming Congress, except for black House members from deliberately drawn black-majority districts, like Cedric Richmond, of New Orleans.

Cassidy pitched his campaign to the evolving political reality of the state and region and to the current wave of dissatisfaction with Obama. His favorite number was 97, representing the percentage of the time Landrieu voted in support of Obama’s agenda in the Senate.

“President Obama is an unpopular president,” Stockley said, “and Sen. Landrieu is being punished for being in the party of the president. It has a little less to do with her and it has everything to do with the environment.”

Landrieu did face problems of her own. She had to fend off accusations that she actually lives in Washington and not Louisiana, and she paid back more than $30,000 to the U.S. Treasury from her campaign funds after it came to light that — in violation of Senate rules — she had spent money from her official Senate office account for chartered campaign flights over a period of a dozen years.

The Republicans seized on both issues, bolstered by a flood of spending on political advertising by conservative outside political organizations that, in the runoff campaign, dwarfed the meager support Landrieu received from Democratic and progressive groups, who largely abandoned her once the Nov. 4 results were in. But as former Louisiana Democratic U.S. Sen. John Breaux joked at a Landrieu campaign rally, it often seemed that Cassidy’s main answer to questions during the campaign was, “Obama, Obama, Obama.”

“I am surprised, to be quite honest, that his campaign has been as successful as it has,” said Pearson Cross, a political science professor at the University of Louisiana at Lafayette. “He’s not a particularly charismatic individual. He’s not a great communicator. He hasn’t really burned the candle on the road. He hasn’t presented himself day and night, meeting everyone in Louisiana.

“But apparently, judging by the polls, he hasn’t had to.”

Follow Gregory Roberts on Twitter, @GregRobertsDC. For more coverage of government and politics, follow The Advocate politics blog at http://blogs.theadvocate.com/politicsblog.