Democrats were cock-a-hoop because U.S. Sen. Mary Landrieu’s chances of re-election got a boost when she came out against putting deadly weapons in the hand of criminals and lunatics.

Polls showed that the vast majority of Louisiana voters applauded her common sense.

But wait. The Republicans are celebrating because pinkos who try to emasculate the Second Amendment are anathema in these parts. Pollsters have determined that Landrieu’s assault on the constitutional rights of unoffending citizens could rule out a fourth term next year.

Only two weeks after 85 percent declared themselves on Landrieu’s side, she is suddenly toast? Louisiana voters must hang their heads in shame for being so fickle.

Or maybe they should wonder which side is cooking the books. The smart money says both of them. It is remarkable how many polls vindicate the politicians who pay for them.

The latest brouhaha comes after Landrieu voted for a bill requiring background checks for gun-show and online gun sales. A more-modest proposal could hardly be imagined, but it doesn’t take much to get the NRA up in arms, and Landrieu faced a ticklish decision. She evidently hemmed and hawed right up to the end. Most of her colleagues voted yea too, but filibustering Republicans carried the day.

Not only had Landrieu’s vote been in vain, but she had handed the GOP a stick to beat her with in next year’s election. Her only excuse for the vote was that she hoped to “reduce gun violence,” and she rushed to proclaim her devotion to the Second Amendment from the rooftops.

But the main challenger for her Senate seat, Bill Cassidy, Republican Congressman from Baton Rouge, announced he would have voted against expanding background checks, and we can look forward to campaign commercials listing wishy-washiness on guns among Landrieu’s sins. If the accusation were to stick, Landrieu would indeed be toast.

To judge from Democratic polls, however, it hasn’t stuck so far. In fact, the vote for more background checks made a lot of sense to the heavily armed electorate back home. No fewer than 45 percent of registered voters were now more likely to vote for Landrieu.

Republicans did not like those numbers, so they came up with their own. Defend Louisiana, a group headed by state Rep. Jeff Thompson, R-Bossier, and characterized by an enthusiasm for guns that borders on the rabid, produced a rival poll. It reached the opposite conclusion, almost exactly at that. This time, because of her vote for background checks, 48 percent of voters were less inclined to vote for Landrieu.

There is no telling which side is right, if indeed either is. Trust nobody is the best policy. It is unlikely that any mathematical sleight of hand occurred, however, for the great art of tendentious polling lies in how the questions are framed.

When Republicans and Democrats can adduce data to prove they both won on the same issue, we have strayed far beyond the realm of science. The parties are best left to bicker on their own. The election is too far off for the public to pay attention.

A GOP spokesman has already declared that Landrieu faces “an uphill battle for re-election in 2014,” but his evidence for that is the Thompson poll. Democrats can predict a breeze with equal confidence.

Democrats in statewide office sometimes seem headed for extinction in Louisiana, and the GOP will be licking its chops over the Senate race. But that is what it does every six years. Landrieu is always prominent on the list of Democratic senators ripe for ousting, but keeps squeaking by regardless.

It is true that she couldn’t have faced weaker challengers if she had chosen them herself, and maybe Cassidy won’t be such a patsy as he tries to hang gun control and Obamacare around her neck.

After 16 years of studiedly centrist votes in the Senate, however, Landrieu has a pile of campaign money and host of powerful friends, even in the upper reaches of the state GOP.

There’s no point trying to predict the outcome of this election yet. We’ll have to wait for a poll we can trust.

James Gill can be reached at