UPDATE, 3 PM: After “What is it, why did we do this and how can we prevent it from happening again?” David Letterman asked Sen. Jeff Flake (R-Ariz.) and Sen Martin Heinrich (D-N.M.) tonight of their new Discovery Channel reality program Rival Survival, in which the two politicians survived six days and six nights on an island with none of life’s necessities — except a camera crew.  Interestingly, Dave gave the guys their only grilling of a media day that included doing the cable news TV rounds in the morning. As they had done hours earlier on MSNBC and Fox News Channel, the two men again told the story about having  had to swim shark-infested water to get to the  island. “There seemed to be guys in a boat following you as you swam to the first island. So why didn’t you just ride in with the camera guy?” Dave asked, unimpressed.

The senators again delivered their line about having participated in a TV reality series to demonstrating to their colleagues on Capitol Hill that Democrats can have lunch with Republicans. Seriously. “To me it’s embarrassing for all of us… that we have to repeat this way of behavior in Congress,” Dave said sternly, adding,  “Anybody’s who’s got kids knows that you don’t have to agree on everything to like one another.”

“You were unable to start a fire! That’s embarrassing for both of you!” Dave chided later.  “You’re from New Mexico and you’re from Arizona — you two couldn’t start a fire — come on!”

“I don’t need to prove anything,” Letterman said when the politicians noted Discovery hoped to do more episodes with other odd-couple pairings.

PREVIOUS, 1:29 PM: Having survived six days and six nights on an island,  Sen. Jeff Flake (R-Ariz.) and Sen. Martin Heinrich (D-N.M.) made the TV talk rounds today to plug the Discovery Channel special that resulted, and weigh in on Ebola and Obama.

In a Rival Survival clip shown this morning on MSNBC’s Morning Joe, Henrich is seen shucking clams, building a shelter, and spearing fish; Flake is seen snarking. “[Heinrich] built the structure and everything, so I applaud him —  that’s more than I thought a Democrat could do. They usually stop at around 5 PM —  that’s union rules,” he says.

Joe Scarborough noticed this. “He builds the shelter, gets the fish,he shucks the clams — what do you do other than sit around making ideological statements about him quitting at 5 o’clock?” he asked.

“It’s the first time a Republican has had a Democrat do that, rather than the other way around,” Flake continued to snark. It plays better on an island.

The two politicians were asked to weigh in on Today’s TV News Talking Point: Nurse Kaci Hickox, who was put in isolation Friday discoverychannel2after returning to New Jersey from a month in Sierra Leone — part of a policy announced by New Jersey Gov. Chris Christie and New York Gov. Andrew Cuomo to quarantine all health care workers who have had contact with Ebola patients in West Africa. (Today, after she said the quarantine violated her rights, and after testing negative for Ebola, she was discharged.)

Henrich advised using common sense. “I think the governors overreacted a little, but I understand the concern” he said. “I think there is a happy medium here where we don’t need [a doctor back from treating Ebola patients] to be at a bowling alley for a few days but where we can monitor folks in their home. We need to encourage health care workers to go to West Africa — we need to snuff this out in West Africa, and not let let this go global.” Flake echoed his thoughts.

MSNBC talking head Donnie Deutch stopped by, in his capacity as an “image expert,” to declare Rival Survival “brilliant,” because “we sometimes forget you guys … are human being. … This is what Americans want.”

Then the politicians headed to Gretchen Carlson’s Fox News Channel show, where Carlson wondered, rhetorically, why Obama isn’t doing more to help campaigning Democrats. That gave Flake his opening to declare Obama’s popularity so low — how low is it? —  that most candidates’ are polling “well ahead” of Obama. Rival Survival, Flake explained, is a metaphor for the “extreme circumstances” of Washington politics, which he described as “dysfunctional.” The Discovery show demonstrates, he said, that while he and Heinrich disagree on most political issues, “We can still work together.” Because working together in Washington, to demonstrate that they can work together in Washington, is too complicated for viewers?

“I have to assume since you are both here, you did both survive,” Carlson observed.

Tonight, they’re visiting with David Letterman on CBS.

Discovery Channel recorded the two as they spent six days and nights on an island, where they swore to find common ground. The two political enemies spent six days together on Eru, one of the Marshall Islands, which Discovery describes as a deserted destination where the reefs are fraught with venomous stonefish, lionfish and scorpion fish. It’s also home of the largest shark sanctuary in the world — more than 2 million square miles of black tip, oceanic white tip, gray reef, bull and tiger sharks, among others.

Using only their wits — and three items of their choosing — the senatorial adversaries foraged for stuff.

Rival Survival is produced for Discovery Channel by Renegade, producers of Discovery’s popular dump-people-in-the-middle-of-nowhere series Naked And Afraid. But don’t worry, the senators will be clothed.

Flake served in the U.S. House of Representatives for six consecutive terms from 2001-13 prior to his election to the U.S. Senate. Last year, Flake and Sen. John McCain (R-AZ) were part of the “Gang of 8″ who teamed on immigration. Heinrich, a member of the Senate’s Energy and Natural Resources Committee, is a self-described “conservationist” and progressive.