"If there's one thing we've learned in this election season, by the way, it is that a few words from Bill Clinton can do a man a lot of good," Mitt Romney said to peals of laughter during a speech at the Clinton Global Initiative on Tuesday. "All I got to do now is wait a few days for that bounce to happen."

Romney was joking -- but not really.

Looking back at the last month of the campaign, which, by the by, has been President Obama's best month of the campaign, it's impossible to dispute the remarkably positive influence that the former president has had on the candidacy of the current occupant of the White House.

The most obvious example is Clinton's speech at the Democratic National Convention, a tour-de-force in which the former president  framed the choice of the 2012 election as well -- many people say better -- than Obama had done to date.

"President Clinton is an unparalleled arbiter of economic success and progress," said Neera Tanden, the president of the Center for American Progress and a longtime Clinton loyalist. "So for him to validate President Obama’s economic policies but more importantly, assure people that things will get better – and stake his reputation on it – I believe that has made a significant impact in both Democrats and independents feeling better about the direction of the economy."

Even Republicans now acknowledge that Clinton's speech -- and the positive press bump that it received -- is currently contributing to the slippage they are seeing nationally.

Obama, too, has taken to channeling Clinton in his own stump speeches;  Clinton's "arithmetic" line about how to balance budgets has become a major Obama talking point.

Then there are the campaign ads in which Clinton has been a regular participant, the most prominent of which is this one that hit the airwaves in late August:

Clinton's soaring popularity -- an NBC/Wall Street Journal poll earlier this month showed him with the highest positive ratings they had ever measured for him -- as well as his demonstrated appeal to the political center and proven track record on the economy make him, without question, Obama's top surrogate in this race.

To be clear: Barack Obama is the single person most responsible for the patch of success his campaign is experiencing. He is the one who is stumping around the country, raising the money and running the ads that have helped define the parameters of the race. Heck, he's the one who has empowered Clinton -- the husband of his one-time rival -- to play such a prominent role in the campaign.

At the same time, it's hard to argue that Obama is in a better place today than he would be without Clinton's heavy involvement in the campaign. Clinton has given the economic argument forwarded by Obama a grounding in the real world, a sort of flesh-and-blood component that the incumbent struggled to conjure on his own for much of the year. Clinton is the populist truth teller to Obama's soaring rhetorician.  It's a yin and yang thing that has worked very, very well for Democrats of late.

If Obama wins, the victory will be his and his alone. But he'll have benefited from a big assist from Bill Clinton.