* After conventions, focus back on economy
* McCain and Obama hit campaign trail
* Obama camp criticizes McCain speech
By John Whitesides, Political Correspondent
ST. PAUL (Reuters) - Presidential rivals JohnMcCain and Barack Obama, back on the campaign trail after theirparty conventions, clashed over the ailing U.S. economyFriday as unemployment hit its highest monthly rate in nearlyfive years.
Hours after accepting the Republican nomination, McCain andrunning mate Sarah Palin opened a two-month sprint to the Nov.4 presidential election in Wisconsin and Democrat Obama headedto Pennsylvania to tout their cures for the economy.
A new report showed the U.S. jobless rate unexpectedly shotup to 6.1 percent in August, adding to public worries about aneconomy that opinion polls show was already the top concern forAmerican voters.
"Americans are hurting and we must act to create jobs,"McCain said in a statement, promising to enact a jobs programand retrain workers for a changing market.
He rapped Obama's tax proposals, which include a large taxcut for lower- and middle-class workers but would increasetaxes for the wealthiest Americans. "The American people cannotafford a Barack Obama presidency," he said.
Obama, an Illinois senator, said the job losses showed theneed for change in the economic approach used over the lasteight years under President Bush. He said McCainwould mean more of the same.
"Today's jobs report is a reminder of what's at stake inthis election," he said in a statement. "John McCain showedlast night that he is intent on continuing the economicpolicies that just this year have caused the American economyto lose 605,000 jobs."
The renewed battle on the economy came the day afterMcCain's acceptance speech concluded the Republican convention.Obama accepted the Democratic nod at his party's convention theweek before.
Mindful of Bush's low public approval ratings, McCain hassought to distance himself from the current administration, and inhis speech, he touted his credentials as a reformer and portrayedhimself as the real agent of change in the race against Obama.
'I WORK FOR YOU'
"I don't work for a party. I don't work for a specialinterest. I don't work for myself. I work for you," McCain saidin an address that included only passing criticisms of Obamaafter a four-day convention marked by scathing attacks on theDemocrat.
"I've fought corruption and it didn't matter if theculprits were Democrats or Republicans," McCain said as Palin,the relatively unknown Alaska governor who he chose last weekas his surprise running mate, watched from the stands.
McCain and Palin flew out of Minnesota immediately afterthe convention ended with the traditional sea of balloons,heading to Wisconsin for a morning campaign event and later inthe day to Michigan and Colorado and on Saturday to NewMexico.
McCain trails Obama slightly in most national opinion pollsas they head into the election but he promised the Republicanfaithful at the convention he would win.
Outside, police arrested 250 anti-war protesters marchingto the venue after using flash grenades and teargas to herdthem onto a bridge. Inside, McCain was interrupted severaltimes by anti-war protesters. Police hauled two women out ofthe arena.
McCain has been one of the most outspoken supporters ofU.S. military involvement in Iraq.
The Obama campaign said McCain talked about change but showedlittle interest in it.
"You can say 'change' 10 times in a speech, 15 times inspeech. You can say 'reform.' The truth is, there's not aneconomic policy that was pointed to last night or at all inthis convention that's one iota different from George Bush,"Obama adviser Robert Gibbs said on MSNBC.
Opinion polls show majorities favor Obama's leadership on the economy, although McCain is usually favored on foreign policy issues.
With the conventions and the selections of running matesout of the way, the next big campaign milestone is the first ofthree debates, on Sept. 26 in Oxford, Mississippi.
Palin, the Alaska governor, meets Obama's No. 2, DelawareSen. Joe Biden, in a debate between vice presidentialcandidates on Oct. 2 in St. Louis.
Palin has been shielded from most public events and has notdone new interviews since she was picked for the job in a movethat ignited a blaze of support among Republican socialconservatives. She heads out on her own on the campaign trailnext week.
(Editing by Frances Kerry)