VP pick behind him, Obama returning to campaigning

His running mate selection sealed, Barack Obama resumed pre-convention campaigning with a scheduled stop in Wisconsin on Sunday in the run-up to accepting the Democratic nomination for president.

Fresh from introducing fellow Sen. Joe Biden as No. 2 on the ticket, Obama set his sights on Wisconsin, Iowa, Missouri and Montana before the nomination becomes his Thursday in Denver. Biden returned to Delaware after the first joint appearance Saturday in Springfield, Ill., where Obama had begun his campaign in February 2007. Obama on Sunday headed to Eau Claire, Wis., a city of 65,000 about 85 miles east of St. Paul, Minn., site of the Republican convention next month. He was expected to discuss ways to stimulate the economy and help middle-class families.

In his campaign debut, Biden criticized Republican John McCain as a captive to the "right wing of his party" who is insensitive to woes facing the middle-class.

Obama introduced Biden, a Senate veteran who heads the Foreign Relations Committee, as "a leader ready to step in and be president" and with much expertise in world affairs.

McCain, who had no public schedule Sunday, told CBS News that Biden was a "wise selection" who will be formidable. But the Arizona senator was critical of the Obama-Biden ticket on foreign policy, citing disagreements with Biden's decision to vote against the first Gulf War as well as his position that Iraq should be divided "into three different countries."

Democrats coalesced quickly around the 47-year-old Obama's selection of Biden, who provides foreign policy heft to the ticket.

Biden, 65, emerged as Obama's choice after a secretive selection process that reviewed at least a half-dozen contenders — but evidently not Hillary Rodham Clinton, the former first lady who was Obama's tenacious Democratic rival.

McCain, who has not announced his running mate, holds a 2-1 lead over Obama as more knowledgeable on world affairs and as better suited to be commander in chief, according to an ABC News-Washington Post poll released early Sunday. The same poll, which gave Obama a slight 49 percent to 43 percent lead, found that three-fourths said the addition of Joe Biden as Obama's running mate would make no difference in their vote, while the remainder were evenly split on whether it would make them more or less likely to vote for Obama.