Barack Obama stands with Bruce Springsteen during a campaign rally at the Cleveland Mall in this Nov. 2, 2008 file photo. After originally saying he would sit the 2012 race out, Springsteen appeared at an Obama campaign rally with former President Clinton on Oct. 18th.

Analysis:

My declaration this morning that Bruce Springsteen's endorsement of President Obama's reelection read like a "suffering liberal" who's only jumping into action for the president grudgingly drew quite the online backlash.

The dissenters include Bruce fans - who might be a touch blinded by The Boss' light - and also strong supporters of the president, with quite a bit of overlap, surely.

The alternate view, as advanced by Salon's Joan Walsh among others, sees Springsteen's late decision to get involved in 2012 as validation of the Obama message, rather than a question mark surrounding his record.

I'm not suggesting that Springsteen's support for Obama is anything less than genuine. And I'm not understating the potential base-motivating impact of this rock-star endorsement, particularly when combined with that of former President Bill Clinton's help, with that duo appearing jointly today in Ohio.

But Springsteen's belated decision to get actively involved in the reelection speaks to a larger challenge that will confront the Obama campaign all the way through Election Day. That challenge is far less about getting voters to support Obama over Romney than it is about getting them to line up at the polls Obama once again, under much different circumstances than four years ago.

Few people believe Obama can expect to win by a larger margin, nationally or in key battleground states, than he did in 2008. That means he's appealing to a universe of voters who consist almost entirely of people who were inspired by his message four years ago, but aren't quite where they were in 2008.

That means Obama has to start a similar fire with a smaller spark. This week's ABC News/Washington Post poll was the first to show strong enthusiasm for Mitt Romney's candidacy exceeding that for Obama's; by contrast, Obama supporters were twice as likely to be highly motivated than John McCain's four years ago.

The endorsement statement posted by Springsteen last night does contain a spark, but it's a slightly damp one.

It contains not a word of criticism for Obama or his record. Yet the poetry that marked Springsteen's support from the last go-around - Obama "speaks to the America I've envisioned in my music for the past 35 years," he wrote at the time - is largely gone.

Springsteen seems wistful in describing 2008. He's as workmanlike as one of his protagonists, though, in describing 2012 - if not quite grudging in lending his star power, certainly not dreaming any longer.

"Last time around, he carried with him a tremendous amount of hope and expectations," he writes. "Unfortunately, due to the economic chaos the previous administration left him with, and the extraordinary intensity of the opposition, it turned into a really rough ride. But through grit, determination, and focus, the President has been able to do a great many things that many of us deeply support."

Three times Springsteen stresses that Obama is the right choice "for me." Four times he references "the choice" between Obama in Mitt Romney in explaining his support.

Perhaps The Boss is yielding to a construct of the race that may be inevitable for a president seeking reelection. It has been the Obama team, moreover, seeking to make the election into a choice between competing visions and very different people, with rough and early attacks on Romney.

Springsteen, it should be recalled, was a vocal and visible supporter of John Kerry's and Obama's, in 2004 and 2008. He had previously spoken about his desire to stay on the sidelines in 2012, to preserve his "political capital" and also, he suggested, because of some lingering disappointment about the president's handling of the jobs and housing markets.

"I would like to have seen more activism in job creation sooner than it came. I would like to have seen people helped out, seen some of these [home] foreclosures stopped somehow," Springsteen said in February.

With the diminishing number of undecided voters, this race is fast developing into one of base inspiration for both sides. Like any great artist, The Boss knows his audience.