DENVER (October 4, 2012)—GOP presidential nominee Mitt Romney barreled out of the first presidential debate energized by a solid performance that showed his determination to take it to President Barack Obama.

Most analysts agreed Thursday that Romney was the clear winner of the debate Wednesday in Denver and several described the president’s performance as dispassionate, dispirited and tired.

The president, however, intent on keeping his momentum from stalling, was warning Americans that his Republican rival's policy prescriptions for a fragile economy are more fantasy than reality.

Standing toe-to-toe with the president Wednesday for the first time in the campaign, Romney held his own at a time when there already were signs that the race is tightening in some of the battleground states where Mr. Obama has enjoyed an advantage.

Mr. Obama kept his cool and signaled that he won't let up on his message that Romney's plans on taxes, health care, the deficit and more just don't add up.

The candidates sparred Wednesday over their differing approaches to growing the economy.

Mr. Obama said that Romney's tax agenda would not reduce the deficit and said it would include a massive tax cut for the wealthy and more military spending.

The president cited former President Bill Clinton, suggesting the nation should return to the Clinton-era tax rates he says would lead to economic growth.

Mr. Obama says simple "math" and "common sense" show Romney's approach is not a recipe for job growth.

Romney responded that virtually everything Mr. Obama said about his tax plan was inaccurate.

Romney said his plan will cut taxes, reduce spending and grow the economy.

"I will lower taxes on middle income families,” he said.