WASHINGTON — Even as his turn on the global stage hit an emotional peak Thursday with a speech before a cheering crowd of more than 200,000 in Germany, Barack Obama faced new evidence of stubborn election challenges back home.
Fresh polls show that he has been unable to convert weeks of extensive media coverage into a widened lead. And some prominent Democrats whose support could boost his campaign are still not enthusiastic about his candidacy.
Several new surveys show that Obama is in a tight race or even losing ground to Republican John McCain, both nationally and in two important swing states, Colorado and Minnesota. One new poll offered a possible explanation for his troubles: A minority of voters see Obama as a familiar figure with whom they can identify.
Republicans are moving to exploit this vulnerability, trying to encourage unease among voters by building the impression that Obama's overseas trip and other actions show he has a sense of entitlement that suggests he believes the White House is already his.
In Ohio on Thursday, McCain hit that theme: "I'd love to give a speech in Germany . . . but I'd much prefer to do it as president of the United States, rather than as a candidate for the office of presidency."
Obama also faces discontent from some of Hillary Rodham Clinton's most ardent supporters, who are put off by what they describe as a campaign marked by hubris and a style dedicated to televised extravaganzas.
Susie Tompkins Buell, a major Clinton fundraiser, said: "The Clinton supporters that I know are bothered by these rock-star events. These spectacles are more about the candidate than they are about the party and the issues that we care about."
Obama is to return home Saturday after a nine-day trip that has produced some of the most memorable images of the campaign. Speaking in Berlin before a sea of young faces, the presumed Democratic nominee echoed a famous line from President Reagan, who, at Brandenburg Gate, implored Soviet counterpart Mikhail S. Gorbachev to "tear down this wall."
"The walls between races and tribes, natives and immigrants, Christian and Muslim and Jew cannot stand. These now are the walls we must tear down," Obama told the warmly enthusiastic crowd in Tiergarten park. He spoke from a stage constructed near the Victory Column, a soaring monument to Prussian military triumphs.
