In 2000, when we were discussing vice-presidential choices with Al Gore, my partner Tad Devine conceded that Joe Lieberman would be an immediate hit; but he believed Lieberman would prove a long-term bust. He told Gore: “What you need is Mr. October, not Mr. August.”

Barack Obama got both when he picked Sen. Joe Biden. The Delaware Democrat immediately demonstrated that he was a happy warrior who could take the fight to McCain, stand up for Obama and connect with blue-collar voters and Catholics. Yet by late October, the conventional wisdom strangely had turned, devaluing Biden’s role and his appeal, and reporting that the supposedly gaffe-prone candidate had been hidden away after stating that Obama would be “tested” by a foreign crisis in his first few months in office.

Reporters have focused far more attention on Joe the Plumber than on Joe the Veep, Joe the Validator, Joe the Defender, Joe the Political Partner. McCain, who probably shouldn’t mention V.P. picks outside a confessional, scoffed at Biden last weekend as “the gift that keeps on giving”—despite the fact that Biden has helped deliver constituents and states and, hours from now, will help deliver the Presidency itself to Barack Obama. Standing behind McCain on the stage as he spoke, a sour-looking Cindy McCain didn’t even crack a smile. I suspect she knows the reality—of the race and of the value of the respective running mates.

A reality check is overdue. I confess I take the matter somewhat personally: I was there watching as, first Joe Lieberman and then John Edwards failed to help, and probably even hurt, Democrats in two agonizingly close battles. In the 2000 vice presidential debate, I’ll never forget Democratic strategist Carter Eskew, one of Al Gore’s oldest friends, calling me repeatedly and plaintively saying, “Oh God, Oh God” as Lieberman barely spoke up for Gore and blithely laid down before Cheney. That single encounter transformed Cheney from the least popular of the four nominees to the most popular overnight.

Biden, in contrast, was relentlessly strategic in his vice presidential debate. He debated McCain, ignoring the ill-informed Palin, and defended Obama, not himself. When the post-debate surveys came in, Biden had swept every one of them.

Biden has been a powerful advocate on the campaign trail and he has done it with a kind of Irish panache, joyously informing a weekend rally of the “great” news that “just today, Vice-President Cheney came out and endorsed John McCain.” He’s pushed back against every GOP distortion. He’s left his audiences whooping and wishing for more as he’s held his stump speech to a disciplined 15 minutes.

While Palin was making a messy national spectacle of herself, Biden conducted more than 200 interviews with local reporters—generally a better investment for V.P. candidates, who invariably have trouble cracking the national media but can leave a big footprint state by state. Palin undoubtedly would have created another batch of lurid headlines had she attempted such a feat.

There’s another difference. Palin delivers a base that has nowhere else to go. Biden widens the Democratic ticket’s base. His popularity with Catholics, seniors and blue collars is likely to help deliver Pennsylvania. The state has been touted as McCain’s last (far-fetched, in my view) hope. But Biden is from Scranton and he’s a Pennsylvania kind of guy. Indeed the Obama operation has largely left Pennsylvania campaigning to Biden, enabling the Presidential nominee to nail down votes elsewhere. And across the border, in Ohio, data show that Biden makes moderates more likely to vote for Obama, while Palin pushes them away from McCain.

In the last days of the 2008 contest, the cable airwaves, the Internet, and to a lesser extent the print press have been filled with implausible scenarios for a McCain comeback—or in the alternative, recurring speculation about what Palin will do next. Drawing far less notice is what Joe Biden has done—which is to help elect the next President. In July, only 15 percent of respondents said the vice-presidential choices would influence their vote. Today, according to the CBS/New York Times poll, 32 percent say that the two V.P. choices have influenced them. The verdict? While 59 percent say Palin isn’t up to the job, 74 percent think Biden is.

On Wednesday morning, I believe Mr. October will become Mr. Vice President-elect. And he’ll be one of the reasons Barack Obama is soon called “Mr. President.” It hasn’t been the flashiest, most riveting story line—how could anyone compete with the train wreck of Sarah Palin? But after watching his performance these past two months, I sure wish we’d had Joe Biden as a running mate in 2000 or 2004.