Sixteen hours between Tuesday evening and Wednesday morning on Capitol Hill brought out the best and the worst in our leaders.

The worst: With just a week to go before the all-important deadline for the congressional supercommittee to come up with a plan to avert a looming debt catastrophe, Senate Minority Leader Mitch McConnell left his office at 6:58 p.m. and went home for the night.

Two minutes later, as The Post’s Paul Kane observed, Senate Majority Leader Harry Reid did the same, decamping for his home at the Ritz-Carlton residences in the West End. He must have been exhausted from the day’s hard work: A 15-minute meeting with House Speaker John Boehner to discuss the progress, or lack thereof, of the supercommittee. It was the first and only meeting the two leaders had on the topic since the supercommittee was formed.

Yet the morning after this failure of leadership, there was a sign of hope: 45 lawmakers – a bipartisan and bicameral group – assembled in a House television studio to urge the dozen supercommittee members to make the unpopular decisions needed to fix the debt problem.

“Supercommittee, we’ve got your back,” said Sen. Saxby Chambliss (R-Ga.).

“We’ll have your back,” agreed House Minority Whip Steny Hoyer (D-Md.).

“We are here,” said Sen. Mike Crapo (R-Idaho), “to make sure the supercommittee knows that we’ve got its back.”

“We got their back,” Sen. Mark Warner (D-Va.) concurred.

Their clichés were tired, but their bravery was refreshing: Democrats willing to cut Medicare and Social Security, and Republicans willing to raise taxes, because that’s what’s in the national interest.

As somebody dedicated to mocking politicians for their misdeeds, I’m often asked whether there are any good ones. Well, on the stage Wednesday morning was a group of lawmakers engaged in the best tradition of public service. (For a full listing of these profiles in courage, you can see the House members’ names here, and the senators here.)

In all, there are 147 members of the self-proclaimed “Go Big Coalition” — and that’s the problem. It represents not even a third of the 535 members of Congress. While some members of leadership were in attendance Wednesday (Hoyer, Senate Majority Whip Dick Durbin and Republican Conference Chair Lamar Alexander), not one of the top leaders -- Reid, McConnell, Boehner, House Minority Leader Nancy Pelosi, Majority Leader Eric Cantor – has joined the effort.

In fact, the supercommittee is getting little support from leadership on either side, and some, such as Reid, have been overtly hostile to efforts to forge a debt compromise. That has made the supercommittee members, who were appointed by the leaders, far less willing to cut a deal: Though they know that the panel’s failure to act would further undermine confidence in government, it wouldn’t be as devastating as having the entire Congress vote down the supercommittee’s recommendations next month.

Back in July, when the compromise was forged to create the supercommittee, the nation’s attention was focused on the effort. A week before the deadline to reach that deal, President Obama and Boehner gave dueling speeches to the nation. Now congressional leaders are working bankers’ hours, and the public has lost focus: A Politico/George Washington University poll found that 88 percent of Americans are not familiar or only somewhat familiar with the supercommittee.

The lawmakers who crowded the stage Wednesday morning tried to change that. “Most Americans, if they saw this scene behind me, would say, ‘I didn’t think that was possible,’ ” Durbin said, “‘I didn’t think you could bring together so many Democrats and Republicans from the House and Senate to agree on anything.’”

And these guys actually seemed to like each other. Hoyer made a show of celebrating his “fraternity brother” Chambliss and his “partner,” Rep. Mike Simpson (R-Idaho). “The public doesn’t believe that we have good friends across the aisle,” he said. “That’s not accurate.”

It was a rare feel-good moment, but it was brought back to reality during the question time, when a reporter pointed out that Rep. Jeb Hensarling (Tex.), the supercommittee’s Republican co-chair, has said up to that point that he would not compromise any further on taxes, while Republicans are complaining that Democrats haven’t offered a new proposal in a week.

“Failure’s not an option,” Hoyer said. “Our country needs us now.”

Another questioner asked about all the Republicans who had signed a pledge not to raise taxes. “We are ready to make the compromises and build the solutions that can help bring all the parties together,” Crapo said. He and his colleagues, he added, are “ready to stand here and make the kinds of decisions that will help us as a nation to solve our fiscal crisis.”

If only the Go Big Coalition had a majority.