Mitt Romney continues to face questions over the timing of his decision to leave Bain Capital, as the Obama campaign and other Democratic supporters this week stepped up attacks after the release of Bain-filed Securities and Exchange Commission documents.

Election 2012 Blog’s Ellen Nakashima writes that Chicago Mayor Rahm Emanuel, Obama’s former chief of staff, told Romney to “stop whining” in an interview with ABC’s “This Week”:

“Said Emanuel: ‘What are you going to do when the Chinese leader says something to you or Putin says something to you? Going to whine it away?….Defend — if you want to claim Bain Capital as your calling card to the White House, then defend what happened to Bain Capital.’”

There is uncertainty how these attacks will ultimately affect Romney’s campaign. The Fix’s Chris Cillizza writes that Romney’s “Bain problem” is unlikely to end soon, as the SEC documents include what seem to be contradictions about the timing of his departure:

“While most independent fact checkers agree that Romney had no involvement in Bain’s day-to-day operations after 1999, the fact that he was listed on Securities and Exchange Commission documents as chairman and president of Bain creates a fuzziness that allows President Obama’s campaign to continue to hammer away on the issue. That fuzziness was furthered over the weekend by Romney campaign senior adviser Ed Gillespie who said that the former Massachusetts governor had “retroactively” retired in 1999.”

The Fix’s Scott Clement writes that although Romney’s time at Bain may have originally been considered a strength for his economic strategy, these recent attacks may have made Bain no longer an asset for the Romney campaign:

“In May, Americans in states classified as ‘toss-ups’ by The Fix split about evenly on whether Romney's work ‘buying and restructuring companies before he went into politics’ was a major reason to support or oppose him. But by July, a Washington Post-ABC News poll found that the issue was a net negative by a 32 to 20 percent margin. This contrasts with non-toss-up states, where about as many saw it as a positive and negative in both months.”

Wonkblog’s Ezra Klein, however, writes that these attacks are unlikely to have a major effect on voter opinion.

“Anyone expecting a major swing in the polls from these attacks is likely to be disappointed. Remember that most voters who haven’t already made up their minds mostly aren’t paying attention, and voters who live in swing states and haven’t made up their minds have already seen hundreds of ads on this topic and it hasn’t been enough to push them off the fence.”

But Klein expects that the Romney campaign’s defense could yield have a negative long-term impact for the candidate.

“The Romney campaign’s preferred defense is that after 1999, he was ‘sole stockholder, CEO, chairman, and president of Bain Capital’ in name only, and therefore not responsible for any of the decisions made. I suspect this narrative will, in the long-run, prove worse for Romney than the narrative it’s trying to defend against. More on this later.”