Obama, Romney blitz through swing states as campaigns near the finish line

AMES, Iowa – Mitt Romney stepped up his bid to strip President Obama of the popular attributes that propelled his candidacy four years and claim them as his own, casting himself in a formal speech here as an agent of change who would govern as a post-partisan president.

Saying the nation is at a critical juncture, the Republican nominee repeated his newest campaign mantra – that he would usher in “real change” – and summoned Americans to shift course to meet the challenges the country faces.

But as Romney insisted his campaign was on the march — and aides tried to expand the playing field by arguing Minnesota suddenly was competitive — the electoral math lingered as a serious obstacle for the Republican. Fresh polling in the critical battleground of Ohio suggested Obama still holds a slim lead there, and his state campaign chairman acknowledged Romney’s difficulty of taking the White House without Ohio.

The president’s reelection campaign, meanwhile, claimed an insurmountable lead in early voting there and in other key swing states, including Iowa.

Obama mocked Romney’s new campaign theme, saying in an interview with Philadelphia radio host Michael Smerconish that Romney’s policies are “not big changes, they’re a repeat, a relapse of things that haven’t worked for over a decade now.”

In the same interview, Obama again promised to get to the bottom of what happened Sept. 11 in Benghazi, Libya, where U.S. Ambassador Chris Stevens and three other Americans were killed in an attack but he suggested that Republicans have only tried to politicize the issue.

“I’ve always been straight with the American people with the decisions that we’ve made,” Obama said, while Romney “hasn’t been restrained by facts.”

The interview was one of nearly a dozen that Obama conducted on Friday, including one with MTV, from Washington. He heads back to the campaign trail on Saturday with a trip to New Hampshire, followed by stops in Ohio, Florida and Virginia on Monday.

Romney returned to Ohio on Friday night, and is planning to return again on Sunday. The state has become central to his hopes, and he dispatched Ryan there for a bus tour over the weekend.

Sen. Rob Portman, who chairs Romney’s Ohio campaign, told NBC News after traveling the state with Romney this week that he’s “feeling the pressure.”

“If we don’t win Ohio, it’s tough to see us winning the election nationally,” Portman said. “It’s possible, but it’s very difficult.”

The Obama campaign pressed its case on Ohio, with Obama adviser Aaron Pickrell arguing that early voting is showing a high level of activity in counties Obama won four years ago.

In those counties, 12 percent of voters have so far turned out, as opposed to 9 percent of registered voters in Republican counties. And Obama aides said voters in precincts that backed the president in 2008 have so far cast 53,400 more ballots this year than in precincts that voted Republican 2008 — exceeding that same measure in 2008 by 23,400, even accounting for shifted precinct lines since the last election.