Obama's favorability is down while Romney's is moving up, but the two are tied among likely voters in a national poll. Here's our guide to todays' polls and why they matter.  

Findings: Romney is gaining favorability among registered voters, while Obama is losing it. Though 48 percent view Romney unfavorably compared to 43 percent who view him favorably, that's an improvement from a poll out last Tuesday wherein 51 percent saw him unfavorably compared to 40 percent who saw him favorably. Obama is now in the negative, with 49 percent seeing him unfavorably and 47 percent seeing him favorably. In the poll from last week, Obama had 50 percent seeing him favorably and 47 percent unfavorably. 
Pollster: ABC News/Washington Post 
Methodology: Telephone poll of 1,022 adults — including 842 registered voters — August 29 through September 2, with a margin of error of 3.5 percentage points for the full sample and 4 for registered voters. 
Why it matters: The poll points to Obama's "trouble" with registered women, a group which both campaigns have appealed to at their conventions. Now 46 percent view him favorably, compared to 50 percent who view him unfavorably. In April they viewed him favorably 57-39 percent, and in the poll out just last week they viewed him favorably 51-45 percent. Meanwhile, a Pew poll out today found that, among a group polled between August 31 and September 3, 25 percent said their opinion of Romney has become more favorable "in the past few days." During a period before the convention only 18 percent felt that way. (That said, a plurality for both time frames said their opinions had not changed.)
Caveat: The poll was taken before last night's speeches at the Democratic National Convention, at which Michelle Obama gave a speech that garnered praise and much talk of abortion rights. For a fair assessment of how Obama and Romney are comparatively doing on favorability, we'll have to see what happens following both conventions.  


Findings: The two tickets are tied among likely voters in a new national poll. 
Pollster: CNN/ORC International 
Methodology: Telephone interviews with 1,005 adults of which 877 are registered voters and 735 are likely voters August 31 through September 3 with a margin of error for the total sample of +/-3 percentage points and margin of errors for the subsamples of +/-3.5 percentage points.
Why it matters: Since the last time this poll evaluated likely voters, pre-RNC, Romney has only moved a point, indicating that he got a "one-point convention bounce, normal for the modern political era," as CNN Political Editor Paul Steinhauser wrote. However, Allison Kopicki at the New York Times writes that the new numbers indicate that Romney is "at virtually the same level of support among likely voters polled Aug. 22 to 23." 
Caveat: The last CNN poll was the first of theirs to use likely voters, a demographic that often leans Republican. In the most recent poll Obama leads 52 percent to 45 percent among registered voters.  Also, this poll does not show any of the effects of the DNC.