Despite his improved national standing, Mitt Romney has failed to erase President Barack Obama's clear lead in two key battleground states, two new NBC News/Wall Street Journal polls show.
In Iowa, Obama leads Romney by 51 percent to 43 percent. In Wisconsin, the Democratic incumbent leads his Republican rival by 51 percent to 45 percent.
Both telephone surveys were conducted for NBC/WSJ by the Marist College Institute for Public Opinion. The margin for error in the Iowa survey is 2.9 percentage points; in the Wisconsin survey 3.1 points.
The findings point toward the continued challenge facing Romney even after his strong performance in the first debate left him with a lead in some national polls.
Iowa, with six electoral votes, and Wisconsin, with 10 electoral votes, are two of the states that Obama carried in 2008 that Romney hopes to win back in his attempt to amass the 270 electoral votes needed to win the presidency.
The surveys were conducted over a three-day period that included the second presidential debate, in which most observers concluded Obama delivered a stronger performance. But interviews conducted on the day after the debate showed no meaningful change from the ones conducted before that debate. (Read More: Obama Regains His Footing in Feisty Second Debate.)
In fact, notwithstanding the large viewership and media attention to both events, the surveys show little shift in voter preferences since before either debate occurred. Obama led in Iowa by 50 percent to 42 percent before the first debate, and in Wisconsin by 50 percent to 45 percent.
"You have to reset back to mid-September," said Lee Miringoff of the Marist institute. "There were two debates, but you can't tell it from the numbers."
The surveys show a couple of key factors in Obama's lead.
In both states, he runs even with Romney in assessments of who best can handle the economy — neutralizing what the former Bain Capital executive has hoped would be his critical edge in the race. (Read More: Obama, Romney Tax Plans: A Real Case of 'Go Figure'.)
Obama also enjoys an advantage in assessments of him personally in the two states. In Iowa, 54 percent of voters have a positive impression of the president, while 43 percent do not; in Wisconsin, 53 percent have a positive impression while 44 percent do not. A 51 percent majority of Iowa voters view Romney unfavorably, while in Wisconsin, voters split 47 percent to 47 percent on the matter.
And in both states, Obama's edge among women voters — 18 percentage points in both cases — far outweighs his single-digit deficits among men. (Read More: Romney's 'Binders Full of Women' Comment Goes Viral.)
Obama also holds narrow leads — 2 points in Iowa, 4 points in Wisconsin — among voters age 60 or older. Elderly voters are a key Romney constituency nationally.
Even more dramatically, the surveys point to a substantial organizational edge for the Obama campaign in harvesting the support of voters casting ballots early in both states.
In Iowa, for example, Romney leads by 54 percent to 39 percent among voters who plan to vote on Election Day, Nov. 6. But among the 34 percent of the electorate that has already cast a ballot under Iowa's early voting rules, the poll shows Obama received 67 percent to 32 percent for Romney. Among the additional 11 percent that plans to vote early, Obama leads by 55 percent to 39 percent.
In Wisconsin, voters who said they intend to vote on Election Day divide almost evenly — 48 percent for Mr. Obama, 47 percent for Romney. But among the 15 percent who have already voted early or say they intend to, Obama leads by 64 percent to 35 percent.
—By CNBC's John Harwood