President Obama has significant leads over Mitt Romney in Iowa and Wisconsin, two critical battleground states that could serve as a firewall for the president against a late surge by his rival in other places, according to new NBC News/Wall Street Journal/Marist polls released Thursday evening.
In Iowa, Mr. Obama leads by eight percentage points in a state he won four years ago by a slightly larger margin, according to the poll. In Wisconsin, the home of Representative Paul D. Ryan, Mr. Romney's running mate, the president has a six-point lead.
Both polls were taken on Monday, Tuesday and Wednesday of this week, spanning the period just before and just after the second presidential debate, when Mr. Obama turned in an aggressive town-hall performance.
In both polls, Mr. Obama leads Mr. Romney by 19 percentage points among women, a key constituency that both campaigns are courting with a renewed intensity in the last 19 days of the presidential campaign.
The battleground surveys offer a contrasting view of the presidential race from some recent national surveys, which have shown Mr. Romney moving into the lead. A few surveys have also shown Mr. Obama's wide lead among women eroding in the last few weeks.
Iowa and Wisconsin are among eight or nine states that will help decide whether Mr. Obama or Mr. Romney can assemble the 270 electoral votes necessary to win the presidency. Mr. Obama rallied supporters in Iowa on Wednesday.
Mr. Obama had been leading in both states for months. But some recent polls have showed the race tightening in both places after the first presidential debate, when Mr. Obama's performance was seen by some as sleepy.
The polls released Thursday evening suggest that Mr. Obama's campaign retains some of the earlier strength in both states. They indicate that some of the president's support comes from voters who have already cast their ballots during earl y voting in both states.
In Iowa, about a third of the state's electorate has already voted, and the poll suggests that Mr. Obama has dominated that vote. In Wisconsin, about 15 percent of the voters have already cast their ballots.
The polls were conducted among 1,137 likely voters in Iowa and 1,013 likely voters in Wisconsin. Each poll has a margin of sampling error of plus or minus three percentage points.
Follow Michael D. Shear on Twitter at @shearm.
