Rick Santorum isn't the only presidential hopeful encouraged by Mitt Romney's tepid results from Super Tuesday: A top adviser to President Barack Obama's campaign says the results demonstrate Romney's enduring faults.

Romney is a weak front-runner, David Axelrod said in an interview with NBC's Brian Williams.

Axelrod pointed out that Romney diidn't notch a decisive victory despite vastly outspending his opponents, and he suggested that the nature of the campaign -- in which ads attacking fellow Republicans have proliferated -- could be contributing to a fractured field.

[Romney] spent most of his money on negative ads and I think that has dispirited Republicans, Axelrod said. It's hard to unite a party when 80, 90 percent of the messages you send are negative messages about your opponents.

While Tuesday's muddled results all but ensure a drawn-out nominating battle, Axelrod played down any parallel to the 2008 contest between Democrats Obama and Hillary Clinton. He noted that Obama scarcely mentioned Clinton in his ads.

GOP Candidates 'Decimating Each Other'

I've never seen a race quite like this, Axelrod said of the Republican primary season. They are decimating each other.

That internecine fight has succeeded in driving Romney further to the right as he seeks to consolidate conservative support, Axelrod said. He argued that as a result, independent voters are fleeing the ex-Massachusetts governor. A recent Politico/George Washington University poll confirms this: In a hypothetical matchup with Obama, Romney trailed among independents, 49 percent to 37 percent.

The same poll found that Romney's favorability/unfavorability rating stood at 37 percent/52 percent, with the gulf between voters who like and dislike Romney steadily expanding. Obama, his campaign strategist pointed out, had the opposite status at this stage of his 2008 campaign, with a majority of voters viewing the then-candidate favorably.

While Axelrod stressed Romney's potential weakness among independents, exit polls from Super Tuesday again revealed Romney's struggles with conservatives. Self-identified very conservative voters tended to gravitate toward Santorum, who has built his insurgent campaign on the argument that he is the true conservative in the Republican field.