By Amanda Becker

HARRISBURG, Pa. (Reuters) - Democratic presidential candidate Hillary Clinton took her newly energized White House bid on the road on Friday for a tour of crucial "Rust Belt" states Pennsylvania and Ohio, but the campaign's focus was clouded by a newly disclosed cyber attack.

Reuters on Friday reported that the computer network used by Clinton's campaign, which is based in Brooklyn, had been hacked as part of a broad cyber attack on Democratic political organizations, citing people familiar with the matter.

The campaign said a data program maintained by the Democratic National Committee and used by the campaign and other entities was accessed as part of a cyber attack on the DNC. The Clinton campaign said outside experts had found no evidence that its internal systems had been compromised.

On Thursday, Reuters reported that the party's fundraising committee for candidates for the U.S. House of Representatives had also been breached, the second such incident after last weekend's leak of DNC emails.

Revelations from the DNC emails gave the Democratic convention a rocky start, threatening a bid to reunify the party after a bitter primary campaign.

Even so, a Reuters/Ipsos poll released on Friday showed Clinton leading Republican rival Donald Trump by 6 percentage points.

Nearly 41 percent of likely voters favor Clinton, 35 percent favor Trump, and 25 percent picked "other," according to the new July 25-29 online poll of 1,043 likely voters, which overlapped with the Democratic National Convention in Philadelphia.

After a speech Thursday night in which she became the first woman to accept a major party's presidential nomination, Clinton launched a three-day bus tour of Ohio and Pennsylvania, which like other Rust Belt states have been hit by the decline in U.S. manufacturing.

Clinton and her vice presidential running mate, U.S. Senator Tim Kaine of Virginia, on Friday attended a rally at Philadelphia's Temple University, toured a factory in Hatfield and ended the day in Harrisburg. They will continue onto Ohio on Saturday and Sunday.

Clinton is likely to face a tough challenge in such states from Trump, a New York businessman who is trying to win white working-class voters with rhetoric blasting free trade and illegal immigration.

Clinton and Kaine are using the Rust Belt tour to highlight manufacturing successes and discuss how they plan to boost wages for the middle class. In the process they aim to contrast their vision for the country with the one offered by Trump.

"If you’re looking for a kind of pessimistic, downbeat vision of America, we’re not your folks," Clinton said in Hatfield. "We do not buy into that dark, divisive, image that was presented at the Republican convention last week."

Opinion polls show a potentially tight race in Ohio and Pennsylvania, both of which President Barack Obama won in the 2012 election.

"The differences are stark," Kaine said in Harrisburg.

Clinton and Trump are essentially tied in Ohio, where the Republicans held their convention last week, according to an average of polls by RealClearPolitics. Clinton has a lead of 4.4 percentage points in Pennsylvania, the website's average of recent polls showed.

Ohio and to a lesser extent Pennsylvania are among a handful of competitive states traditionally viewed as decisive in presidential elections, because they do not lean heavily Democratic or Republican.

TV VIEWERSHIP LOWER FOR CLINTON

In her speech on Thursday, Clinton, 68, a former first lady and U.S. senator, promised to make the United States a country that works for everyone if she is elected.

"We are clear-eyed about what our country is up against. But we are not afraid," she said. Clinton portrayed Trump as a threat to the country, saying, "A man you can bait with a tweet is not a man we can trust with nuclear weapons."

Trump, 70, sent out a flurry of comments on Twitter on Friday morning lambasting media coverage of the speech as "a joke," calling the address "very long and very boring" and accusing Clinton of wanting to shut down "coal mines, steel plants and any other remaining manufacturing."

He campaigned in another swing state, Colorado, on Friday and was scheduled to visit Ohio next week.

The U.S. television audience for Clinton's acceptance speech was smaller than the viewership of Trump's address a week earlier, according to ratings data released on Friday.

An estimated 29.8 million people watched Clinton across 10 broadcast and cable networks, Nielsen data showed. Trump drew 32.2 million viewers in his July 21 address at the Republican National Convention.

Economic issues will be crucial as the White House campaign enters its final three-month stretch. The U.S. economy grew by only 1.2 percent in the second quarter, far less than expected, the Commerce Department said on Friday.

During the Rust Belt trip, Clinton will detail her pledge to raise wages and create jobs by unveiling a major infrastructure package within the first 100 days of her presidency, and encouraging companies to invest in workers.

The start of the Democratic convention was overshadowed by the resignation of DNC Chairwoman Debbie Wasserman Schultz, who quit over leaked emails showing party officials favored Clinton over her primary rival Bernie Sanders, a U.S. senator of Vermont.

Cyber security experts and U.S. officials said on Monday there was evidence that Russia engineered the release of the emails in order to influence the election. The Kremlin has denied the accusations.

Yet another hack came to light on Thursday, when four people familiar with the matter told Reuters that the Federal Bureau of Investigation is investigating a cyber attack against the Democratic Congressional Campaign Committee, which raises money for Democrats running for the U.S. House of Representatives. The DCCC confirmed on Friday that it had been the target of a cyber security incident.

(Reporting by Jonathan Allen, Amanda Becker, Luciana Lopez, James Oliphant, Amy Tennery, John Whitesides, Alana Wise and Lisa Richwine; Writing by Alistair Bell and Jonathan Oatis; Editing by Frances Kerry and Leslie Adler; Editing by Frances Kerry and Leslie Adler)