How’s this for a re-election slogan?

“Bill Cassidy, protecting Mary Landrieu’s legacy since 2015.”

Sorry folks, couldn’t resist. The irony is simply too delicious.

How else to characterize Louisiana’s newly elected Republican senator, the very guy who won by painting the Democratic incumbent as a patsy for President Barack Obama, fiercely defending his ousted opponent’s signature accomplishment from said president’s ungainly attempt to trash it?

I’m talking, of course, of GOMESA, or the Gulf of Mexico Energy Security Act, the 2006 Landrieu-quarterbacked measure to secure a portion of deepwater drilling royalties for badly needed coastal restoration.

And if that all sounds familiar, it may be because Landrieu so often cited the act last fall while trying to convince voters to look beyond their feelings about Obama and send her back to Washington for a fourth term.

Landrieu didn’t get everything she wanted in the bill, including a timetable reflecting the underlying environmental urgency. The big money — 37.5 percent of revenues collected from drilling beyond 3 miles off the states’ coasts — wasn’t scheduled to kick in until fiscal 2018, which is clearly why Obama’s eying it now. In his proposed budget, released earlier this week, he pitched an out-and-out raid.

“The budget proposes to work with Congress to redirect the distribution of expanded revenue payments expected to start in 2018 for Gulf of Mexico oil and gas leases to programs with broad natural resource, watershed and conservation benefits for the entire Nation, help the Federal Government fulfill its role of being a good neighbor to local communities, and support other national priorities,” it read.

Cassidy’s aggressive response speaks to just how big a deal this would be for Louisiana.

“I will do everything in my power to use my seats on (the Appropriations and Energy) committees to not only block the President’s raid on oil and gas revenues, but fight to increase Louisiana’s share of offshore revenue,” Cassidy said in a press release. “Funding for coastal restoration must remain a promise to Louisiana and other Gulf Coast states.”

None of this is meant to criticize Cassidy, who is doing exactly the right thing. So is his Senate colleague David Vitter, who also has vowed to protect the GOMESA money and who, as a candidate for governor, has a particular interest in preserving the revenue stream.

The question is whether that’s enough.

Republican after Republican has declared the overall budget dead on arrival, and the simple fact that Obama proposed the idea may be enough to make it toxic in some GOP congressional circles.

But the reality is that the GOMESA money is at risk because it’s never had a particularly broad constituency. Some Democrats don’t like anything that encourages drilling; it’s no coincidence that the bill, which expanded production in the Gulf, passed the last time Republicans had a majority. Obama himself was in the Senate then and joined many of his fellow Democrats in voting against it.

Some Republicans don’t like it because they think the money should go toward deficit reduction, and Obama officials cleverly pitched their proposal as not just an environmental move but also a multibillion-dollar boon for the Treasury.

And everyone in Congress represents a state that has its own needs; a measure that benefits just four states — Louisiana, as well as Alabama, Mississippi and Texas — is a juicy target.

Would the administration have tried this had Landrieu won last fall? Hard to say. Probably not if Democrats had retained the majority and she were still Energy chairwoman, but if Landrieu were serving in a GOP-led Senate, who knows?

Given the election results, that’s all moot. The burden now is on Republicans, not just Cassidy and Vitter but Senate Majority Leader Mitch McConnell, House Speaker John Boehner and, of course, House Majority Whip Steve Scalise, the only Louisiana politician to have a seat at the big table.

Cassidy’s statement suggests he’s ready and willing to lead that fight, to push his colleagues the way Landrieu once did, even if there’s nothing specific in it for them.

If he pulls it off, well, that actually would make a pretty good argument for his re-election come 2020.

Stephanie Grace can be contacted at sgrace@theadvocate.com. Read her blog at http://blogs.theadvocate.com/gracenotes. Follow her on Twitter, @stephgracenola.