President Barack Obama is leading Mitt Romney by 7 points among registered voters -- 52 percent to 45 percent -- in a just-released CNN/ORC International poll.

The margin echoes those of other polls released in recent days, and suggests that the barrage of tough advertisements against the presumptive Republican nominee has taken a toll. As CNN notes:

    While Romney's favorable rating has remained steady (47% now compared to 48% in July), his unfavorable rating has jumped from 42% last month to 48% now ... Among independents, the poll indicates Romney's image has taken a beating. In May, only 40% of independents had an unfavorable view of Romney. Now, 52% of independents have a negative view of him.

These polls are, of course, just snapshots in time. But they underscore the problem that Romney's campaign now has on its hands. His image among the public has been largely defined by his opponent. And while Romney has plenty of cash to run ads of his own, time is running out for him to reverse this trend.

Take, for example, the following findings within the poll:

    Sixty-four percent of all Americans, and 68% of independents, think Romney favors the rich over the middle class. And 63% of the public thinks Romney should release more tax returns than he has already made public, a figure which rises to 67% among independents.

UPDATE: 6:15 p.m. -- The recent trend of generally good news for the president continued on Thursday afternoon, with the release of a new poll by Fox News that showed Obama besting Romney by a 49 to 40 percent margin among registered voters. His lead has increased since last month's poll, when he enjoyed a 45 to 41 percent margin.

As with the CNN poll, the primary factor appears to be the barrage of negative ads directed Romney's way.

    The Obama campaign has spent heavily on advertising attacking Romney’s time at Bain Capital and his tax returns. And it appears to be working. Romney’s favorable rating dropped six percentage points since last month and now sits at 46 percent, down from 52 percent in mid-July. At the same time his unfavorable rating went up five points. Romney’s favorable rating has held steady among his party faithful, but it’s down eight percentage points among independents and seven points among Democrats.