Obama tries to regain his stride

WASHINGTON (Reuters) - After a difficult week that sparked Democratic worries, Barack Obama fired back at Republican presidential rival John McCain on Friday with tough ads and a retooled message outlining their differences on taxes.

Obama acknowledged the concerns of his supporters after a week dominated by McCain and his new running mate, Alaska Gov. Sarah Palin, who charged out of the Republican convention on a wave of momentum and unleashed a volley of harsh personal attacks against him.

The emergence of Palin, an anti-abortion and pro-gun conservative who electrified the party's base supporters, seemed to knock Obama off stride and propelled the Republicans into a slight lead in the November 4 election race in a flurry of national opinion polls.

But Obama and his campaign had a clear message to nervous supporters on Friday: Calm down.

"People start worrying. Here's what I can guarantee you -- we are going to be hitting back hard," he said at a rally in Dover, New Hampshire, where he spelled out his plan to cut taxes for most workers and said he would provide three times more tax relief for middle-class families than McCain.

Obama's campaign released three ads hitting McCain as an out-of-touch supporter of President George W. Bush who would be unable to deliver economic improvements or on his promise to change the culture in Washington.

"Things have changed in the last 26 years. But McCain hasn't," one of Obama's new ads says. "He admits he still doesn't know how to use a computer, can't send an e-mail. Still doesn't understand the economy."

In another ad, Obama talks directly into the camera to explain his promise of change. "Because this year, change has to be more than a slogan," he said.

Obama campaign manager David Plouffe released a memo saying McCain had shown he was "willing to go into the gutter" to win the election.

"Today is the first day of the rest of the campaign," he said, promising to respond with "speed and ferocity" to McCain's attacks.

"His campaign has become nothing but a series of smears, lies, and cynical attempts to distract from the issues," Plouffe said of McCain. "As Barack Obama said earlier this week 'enough is enough.'"

MCCAIN WITH HIS OWN ATTACK

The McCain campaign issued its own attack on Obama. "He was the world's biggest celebrity, but his star's fading. So they lashed out at Sarah Palin," the narrator says in a new ad. "How disrespectful."

The McCain camp said the new approach from Obama was designed to hide his lack of achievement.

"What is becoming clear to the American people is the fact that Barack Obama has no record of bipartisan legislative accomplishment, no history of bucking his party and no chance of bringing change," said McCain spokesman Tucker Bounds.

The political firestorm caused by McCain's pick of the virtually unknown Palin as his No. 2 and the biting attacks on Obama by Republicans had drowned the Illinois senator's economic message in the last week. Democratic strategists have worried he seemed uncertain how to respond.

McCain, a four-term Arizona senator, and Palin latched on to Obama's message of change and presented themselves as the true reformers in the race -- a move that seemed to catch Obama's team off guard.

Some Democratic activists also questioned why Obama was left to handle the responses to McCain and Palin's attacks and urged a more active role for his No. 2, Delaware Sen. Joe Biden, and surrogates in attacking the Republicans.

The growing sense of Democratic nervousness was palpable among grassroots activists and elected officials, forcing Obama to ease their concerns.

In New Hampshire, he said Republicans attack Democratic presidential candidates with lies every four years and cited what he described as an old saying from former President Abraham Lincoln.

"He said, 'If you don't stop lying about me, I'm going to have to start telling the truth about you.' That's what we're going to do," he said. "Our focus is on tax policy. John McCain leaves 100 million people out. I lower taxes. He doesn't."

In a conference call, Democratic Sen. Richard Durbin of Illinois criticized McCain for saying at a forum in New York on Thursday that it was easy for him to be "somewhat divorced" from everyday economic challenges of people.

"That evidences why he really isn't going to bring change," Durbin told reporters.

(Additional reporting by Caren Bohan; Editing by Jackie Frank)