COLUMBUS, Ohio — If one place is emerging as a test of Mitt Romney’s ability to capitalize on a new dynamic in the presidential race, it is Ohio, where he is intensifying his advertising, deploying more troops and spending four of the next five days.
Ohio, whose 18 electoral votes are critical to Mr. Romney’s candidacy, has bedeviled him like no other battleground state. His prospects were so shaky two weeks ago that his advisers openly discussed the narrow path to winning the necessary 270 electoral votes without Ohio, which every Republican president in the nation’s history has carried.
But as the race for the White House takes on a new air of volatility after President Obama’s off-kilter debate performance last week — a poll from the nonpartisan Pew Research Center on Monday suggested that Mr. Romney had wiped out the president’s lead among voters nationally — Mr. Romney is displaying new vigor in his fight for Ohio. The state, along with Florida, Iowa and Virginia, is now at the heart of his strategy for the remaining 28 days of the campaign.
Mr. Obama and Mr. Romney are both visiting Ohio on Tuesday, the final day of voter registration here, but Mr. Romney is sticking around for one of his most intensive bursts of campaigning yet. His increased presence is a response to pleas from state Republican leaders to invest more time and attention in the regions where he needs to turn out voters.
“Republicans who were concerned about some of the poll numbers now have a higher degree of enthusiasm,” said Senator Rob Portman, the chairman of Mr. Romney’s campaign here. “We’ve got a great opportunity to keep the momentum going.”
For the first time, Mr. Romney is personally making his case in a new television ad, saying, “Ohio families can’t afford four more years like the last four.” The message, while hardly novel, is welcome among Republicans who have watched with frustration as Mr. Obama’s campaign has dominated airwaves for weeks with a tailor-made operation in Ohio.
Mr. Romney’s problems here have included the Obama campaign’s success at defining him to many voters over the summer as an out-of-touch corporate raider, as well as a state economy that has been more vibrant than the country’s over all. With both the state and national unemployment rates now below 8 percent, Mr. Romney may have less opportunity than he did earlier this year to convince voters when he asks them in his new ad, “The question Ohio families are asking is ‘Who can bring back the jobs?’ ”
Several Republican officials, asked why Mr. Romney has been lagging well behind Mr. Obama, responded it was not because Mr. Romney was not selling here, but rather that his campaign had not been selling him well.
The president’s campaign has overwhelmed Mr. Romney until now in television advertising. In Youngstown, Mr. Romney and his allied groups ran virtually no advertisements through much of September, as Mr. Obama and his Democratic allies showed their ads more than 1,100 times, according to data compiled by the media monitoring firm Kantar Media/CMAG.
Mr. Romney has now increased his advertising in smaller markets across the state, including Youngstown, Zanesville and Lima. He is scheduled to travel the state on Tuesday and Wednesday with Gov. Chris Christie of New Jersey at his side, hoping to keep enthusiasm high among Republicans who have been showing up in greater numbers at volunteer centers across the state this week.
If the Romney campaign is to have a lasting resurgence in the four weeks until Election Day, his advisers say it must come in states like Ohio. But the presidential debate in Denver last week, where Mr. Romney commanded the stage, has provided him an opportunity to reset the contest.
The president’s advisers acknowledged in interviews that Mr. Romney was almost certain to get a “second look” from some Republican-leaning independent voters who had not yet embraced him despite misgivings about Mr. Obama, including in reliably Republican rural areas where Mr. Romney needs a large turnout.
A Republican-leaning voter in the Cincinnati area who was ambivalent about Mr. Romney before the debate said on Monday that she was now solidly on board.