Sen. Jeff Blake (R-Ariz.) and Sen. Martin Heinrich (D-N.M.) sifting water on an island in “Rival Survival.” (Discovery Channel/Discovery Channel)

In “Rival Survival,” a gimmicky and disappointing socio-political experiment airing Wednesday night on Discovery Channel, two U.S. senators “set aside” their political differences to see if they can survive together for a week on a deserted, sun-blasted South Pacific island. It turns out they can, but not impressively so.

Because they’re senators, “a week” means six days. Also they’re allowed to wear clothes — swim shorts, shirts, sandals — so what kind of a “survival show” is this really? As channel-flippers everywhere know, if you’re not naked with your private parts pixelated into pathetic shadows of manhood, you’re not anything in cable’s tough-it-out world of extreme sunburns and starvation.

As opposed to those poor survivalists who volunteer for Discovery’s hit series “Naked and Afraid,” Sen. Jeff Flake (R-Ariz.) and Sen. Martin Heinrich (D-N.M.) are allowed three survival items to share (instead of one each), picked from a collection of machetes, knives, spear-fishing slingshots and a 9-volt battery that might have helped spark a fire, had they chosen it.

Flake, 51, and Heinrich, 43, are dropped off in the ocean near the shore of Eru, a tiny, uninhabited piece of the Marshall Islands. As a storm approaches and sharks and poisonous tropical fish circle beneath them (in the way that sharks and poisonous fish always seem to circle whenever anyone on Discovery steps into an ocean), Flake and Heinrich swim to the island and rather quickly assemble a palm-frond shelter from the rain, just as night falls. Sadly (and also unlike “Naked and Afraid”), they don’t wind up spooning each other for warmth.

So far, so good. On day two, the senators decide this island is too small to provide sustenance, so they make a dangerous swim to a neighboring island, which at least has the benefit of better trash and debris that has washed up on its shore.

The show keeps reminding viewers that these first-term senators, neither of whom is up for re-election this year, are “bitter rivals” who have “voted against each other 74 times in the Senate.” (To say nothing of how many times they’ve canceled one another out during their respective terms in the House of Representatives.) They are followed by a film crew that cannot intervene unless either of the men surrenders and “taps out” of the process.

Whether or not the show is edited to portray him as a bit of a jerk, it’s Flake who starts in with uninspired, needling jokes about liberals: “If it doesn’t work, blame the Democrat,” he says. Also: “[Democrats] usually stop at 5 p.m. — it’s union rules.” While slurping three-day-old rainwater that Heinrich has wisely strained through his shirt and purified by letting it bake in sunlight inside a discarded water bottle, Flake says: “Drink too much of that, you become a Democrat.”

Heinrich is rarely seen taking the bait or making equally cheap jokes about Republican stereotypes. In fact, he’s not really all that interested in the TV camera — what kind of politician is he?

Neither man is shown to be much of an outdoors specialist. They spend hours trying to start a fire with friction, to no avail, even though both were apparently able to build fires at home in their back yards with string and few sticks. When it matters most, they are incapable. Flake goes ahead and supplies the obvious joke about Congress’s lack of results, adding, “I’d gladly vote for any of Martin’s bills if he could just start a fire.”

Subsisting mainly on coconuts that Heinrich pulls out of the trees, the two decide to go spear-fishing among the coral reef, which also proves to be a lot harder than it looks. Heinrich finally brings up a large bivalve to pry open and eat the gooey insides; Flake complains that he doesn’t eat seafood, certainly not sushi, but he’s too hungry to pass it up. (Between them, the narrator notes, they’ve shared 12 measly grams of protein.)

Eventually, perhaps in a state of delirium, the two men have a vague and obligatory conversation about why Democrats and Republicans no longer even talk to one another. They make half-hearted vows to promote communication across the aisle, words that are worth about as much as a drained coconut.

That said, their focus turns to rescuing themselves, tying together a bamboo raft and heading into the pounding surf. They kick and stroke in the same direction toward the boat that will take them away from this misguided and inconsequential ad­ven­ture in public relations. More lip-service is paid to getting along, but don’t be fooled by the forced smiles: Like everyone who has survived one of these survivalist shows, these two seem like they can’t wait to get as far away from one another as possible.

Rival Survival

(one hour) premieres Wednesday at 10 p.m. on Discovery Channel.