As soon as it became official that they would meet in the runoff, Mary Landrieu and Bill Cassidy each received an endorsement Tuesday night.

Cassidy’s came from a spokesman for third-place finisher Rob Maness, Landrieu’s from the Human Rights Campaign, which bills itself as America’s largest organization fighting for “lesbian, gay, bisexual and transgender equality.”

Chalk up two for Cassidy. Not only will Maness supporters be switching to his column, but the Human Rights Campaign vows to be “focused on re-electing Mary Landrieu to the U.S. Senate.” Any campaign ads touting Landrieu’s sterling record on gay rights will no doubt be favorite reading in the Cassidy camp. The endorsement may be a feather in Landrieu’s cap, but it is one for which any Louisiana candidate would say thanks through gritted teeth.

The day after that double-blow to the Landrieu campaign, Gov. Bobby Jindal joined the chorus urging Landrieu’s defeat, although that was too predictable to make much difference, and Cassidy didn’t even bother to show up.

Regardless, the numbers suggest that, barring some spectacular goof on Cassidy’s part, Landrieu’s Senate career is approaching the end.

Sad, but there are consolations. After 18 years in the Senate, she should have no trouble finding an even more lucrative line of work. Former senators don’t wind up under the Interstate 10 overpass; they are more likely to move to K Street, and Landrieu, as her opponents have been pointing out in the primary, has long made Washington her home.

Landrieu finished so narrowly ahead of Cassidy Tuesday that it appears she would be toast already had Maness not been in the race to snaffle almost 14 percent of the vote. Not all the Maness voters are sure to turn out in the runoff, but, if they do, it won’t be for Landrieu.

Maness, the tea party candidate who also enjoyed Sarah Palin’s support, slammed Cassidy as a half-hearted conservative, inclined to wobble on “Obamacare” and gun rights, for instance. But it is the Democrats who are truly beyond the pale in the eyes of the Maness camp, so Cassidy will no doubt do in a pinch. He lost no time burnishing his conservative credentials and pointing out how different he is from Landrieu, by rushing off to a anti-abortion rally Thursday.

The pundits have predicted for ages that Cassidy will win the runoff, and now the opinion polls put him four percentage points ahead. Landrieu is naturally putting a brave face on it and avers that Cassidy can’t expect to win just by harping on her support for President Barack Obama’s policies.

Don’t bet on it. It’s worked so far, with Obama’s dismal ratings proving such a burden on Democratic candidates that the Republicans took over the Senate with an ease that surprised even them. We can expect to hear much more about Obama in the runoff.

If Landrieu brings him up, it may not be to repeat her charge that he is a hard sell in Louisiana because “the South had not always been the friendliest place for African-Americans.” Evidently she hadn’t heard that a couple of decades after the unreconstructed klansman David Duke won a majority of the white vote in runs for governor and the U.S. Senate, racism has entirely disappeared from Louisiana.

Jindal was on hand to put her right. “The only colors we care about down here are red, white, blue — and purple and gold when we cheer our LSU Tigers onto victory on the football field,” he said in a TV interview. Jindal is evidently determined to keep the fictions and clichés coming until he makes it to the White House.

Landrieu must have expected her statement of the obvious to make the GOP fake outrage and demand an apology for the supposed slur on her progressive and enlightened state. Why she said it, we can only guess. Southern racism may work against Obama, but he is not exactly beloved in the rest of the country, either.

Perhaps Landrieu hoped to encourage a strong turnout by the black voters who make up a significant part of her base. Whatever; she has nothing to gain by invoking Obama’s name again.

Turnout overall will be down in the runoff, and there is no reason to suppose that will be to Landrieu’s advantage. The result will not have the national implications that seemed likely before the Democrats lost their majority Tuesday and cost her the clout that was supposed to argue for her re-election.

She has survived strong challenges before, but Landrieu would appear to need more than the gay vote to swing it this time.

James Gill’s email address is jgill@theadvocate.com.