NORFOLK, Va. — Barack Obama is known for his eloquent speeches, but as he tries to regain his poll lead and beat back an energized Republican ticket, he is adding something to his delivery: volume.

Obama has uncorked some thunderous lines in recent campaign stops, showing a measure of emotion he seldom has displayed. His speeches now are laced with indignation as he argues that anyone who sees John McCain and Sarah Palin as vehicles for change is being duped.

At high decibels, he pressed his point Monday that people could pay a heavy price if they make the wrong decision Nov. 4. At stake are constitutional liberties that can mean the difference between freedom and unjustified imprisonment, he told the crowd in Farmington Hills, Mich.

“We may think this is Muhammad the terrorist; it might be Muhammad the cabdriver. You may think it’s Barack the bomb-thrower. But it might be Barack the guy running for president,” he said, referring to the Bush administration’s arrest and detention policies toward terrorism suspects.

Then, the loudspeakers really began to quake.

“Don’t mock the Constitution. Don’t make fun of it! Don’t suggest that it’s un-American to abide by what the Founding Fathers set up! It’s worked pretty well for over 200 years!”

Finally, he said disdainfully of the Republicans: “These people.”

Feistiness is what many Democratic elected officials have longed to see. At the Democratic convention in Denver last month, Pennsylvania Gov. Ed Rendell said Obama needed to show more fight. But he also suggested Obama knew as much. “You’re going to see a new, fighting Barack,” Rendell predicted.

That they’re seeing. Compare the Obama today with what voters saw before the Democratic and Republican conventions: Campaigning in Montana on the Fourth of July holiday, Obama also talked about the right to challenge one’s detention but said it in terms that were not only milder but also more abstract. Sounding more like the constitutional law professor he once was, he made no attempt to humanize the issue.

Although he is turning up the volume, Obama has stayed under control. If he shows too much temper, he risks looking rattled and perpetuating the sideshow, which could distract voters from the slumping economy, rising gas prices and other issues where he feels he has an advantage.

By contrast, McCain seems to be moving in the opposite direction. Once known as a free-wheeling candidate who liked to mix it up with the public and media, McCain has become far more scripted since reorganizing his campaign in July.

He is increasingly controlled, seldom deviating from his basic talking points. He rarely presides over unscripted town hall meetings, which he once called “the essence of democracy.” He has not held a news conference in nearly a month.