COLUMBUS, Ohio (AP) — Republican presidential candidate Mitt Romney is preparing for his second debate with President Barack Obama but taking time to tell voters in Ohio that enthusiasm for him is surging both in this critical state and across the country.

Obama was hunkering down Saturday in Virginia to go over the game plan for the town-hall debate with Romney. But his weekly radio and Internet address on Saturday spoke of an industry that's critical to Ohio, another battleground state and perhaps the most important to his Republican opponent's White House hopes.

"We refused to throw in the towel and do nothing. We refused to let Detroit go bankrupt," Obama said in the address. "GM is back. Ford and Chrysler are growing again. Together, our auto industry has created nearly a quarter of a million new jobs right here in America."

Romney opposed using government funds to help the auto industry go through bankruptcy. Many analysts believe the industry would not have survived if it had relied on private investment for rescue. It's an issue that has dogged Romney in Ohio, where numerous auto parts suppliers benefited from the survival of the big three automakers.

The Obama campaign also released a new TV ad narrated by actor Morgan Freeman noting the challenges Obama inherited and highlighting the president's successes, including saving jobs for American autoworkers and killing Osama bin Laden.

Romney is concluding a week of campaign rallies that saw him drawing larger, more excited crowds than he has through the fall campaign. More than 10,000 people turned out to several rallies, with the campaign saying that more people were signing up to attend events since Romney's strong debate performance last week in Nevada.

"I've had the fun of going back and forth across Ohio, and this week I was also in Florida and Iowa, I was in North Carolina and Virginia. And you know what? There is a growing crescendo of enthusiasm," Romney told a crowd of thousands at a sunset rally Friday in Lancaster, south of Columbus, where he and running mate Paul Ryan appeared together. "There's more energy and passion. People are getting behind this campaign. We are taking back this country."

Saturday will be the fourth of the last five days Romney will spend campaigning in this industrial, Midwestern state — with 18 electoral votes, it's critical to his hopes of winning the White House. His campaign swing comes as he and Republicans criticize Obama for the handling of the terrorist attack on the U.S. Consulate in Benghazi, Libya.

Romney accused Vice President Joe Biden of "doubling down on denial" concerning security at the diplomatic post where the U.S. ambassador and three other Americans were killed. During the vice presidential debate Thursday, Biden said "we weren't told" about the Benghazi consulate's requests for additional security. Although a State Department official told Congress on Wednesday about the requests, the White House said Friday that Biden was speaking just for himself and for the president.

"The vice president directly contradicted the sworn testimony of State Department officials," said Romney, who was eager to stoke a controversy that has flared periodically since the attack. "American citizens have a right to know just what's going on. And we're going to find out."

Romney plans to spend Saturday morning at a hotel outside Columbus, where he'll meet with top advisers and get ready for his showdown with Obama in Hempstead, N.Y., on Tuesday. He returns to Massachusetts in the evening but first makes two campaign stops in Ohio.

After his widely panned performance in the first presidential debate, polls show Obama still holds a slim edge in Ohio. The state is crucial for Romney because his path to winning the 270 electoral college votes he needs is far narrower if he can't win Ohio. Losing here would mean he'd have to win almost all of the other up-for-grabs battleground states.

Obama was in Ohio this week, too, but he was spending the weekend in Williamsburg, Va., preparing for the debate. The president has acknowledged he needs to turn in a stronger performance when the two meet again.

Obama and top aides plan hours of practice sessions ahead of the town hall-style event, including some mock exchanges with Sen. John Kerry, D-Mass., who is playing the role of Romney.

Campaign officials sought to keep details of Obama's preparations secret. But they said the president was working on being more aggressive in responding to Romney and calling the Republican out on issues as well as pointing out what they maintain are Romney's true positions.

While Obama has no public events planned in Virginia over the next three days, his mere presence in the state will drive some local news coverage. And he may make unscheduled visits in the Williamsburg area.

The president practiced for the first debate in Nevada, another battleground state.

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Obama address: www.whitehouse.gov

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Associated Press writer Julie Pace in Washington contributed to this report.