Republican challenger Mitt Romney's pick of the firebrand conservative congressman was meant to put the Midwest state in play in the election and expand the list of vital swing states that could decide who sits in the Oval Office next year.
Obama's visit to Wisconsin, his first since February, appeared to be designed to shore up Democratic support there. Certainly Republicans in the state – buoyed by the recent recall victory of Republican governor Scott Walker – painted Obama's visit as a sign their party could win in November.
"With his visit today, President Obama admits he has a Wisconsin problem," Walker said in a statement issued ahead of a planned Obama rally and fundraiser in Milwaukee. However, recent polls suggest Obama has a lead in Wisconsin, as he does in most swing states and national polls.
Obama won Wisconsin easily in 2008 but Ryan is popular. Some Republican pollsters detected a bump for Romney in the state shortly after Ryan was named his running mate.
Wisconsin's 7.5% unemployment rate is below the national average, but the state's manufacturing industry has been hit hard in recent years. Obama's campaign is focused on running up big margins in Milwaukee and Madison, which are both Democratic strongholds. Obama and Romney will be closely watching the Green Bay region, a swing area that could tip the balance in a close contest.
Vice-president Joe Biden was also out on the campaign trail on Saturday, using an address in New Hampshire to criticise Romney and Ryan, particularly over Medicare and the budget.
"[Romney and Ryan] would deny benefits for 48 million people," said Biden. "What they don't want to tell you is that it would turn Medicare into a voucher program."
Biden then defended Obama 's efforts to reduce federal spending, and claimed the government was merely trying to fix a problem originally caused by Republicans.
"[Romney and Ryan] haven't offered one single, solitary idea to solve the problem," said Biden.
Romney was raising money this weekend in California, in hopes of recovering his fundraising advantage. Last month, for the first time, Obama and the Democratic Party raised more than Romney and the Republican Party – $114m to $111.6m.
The beleaguered Republican candidate has suffered a nightmarish few weeks after a nominating convention in Tampa that was widely seen as a damp squib. Since then he has made several notable gaffes, endured minute examination of his tax returns and been hit hard by the leak of a video shot at a private fundraiser in which he lambasted "the 47%" of Americans who pay no income taxes and get government help.
In response, Romney has opened a new line of attack against Obama, saying the president has failed to deliver on his promise of change. Ryan, campaigning on Saturday in Miami, reinforced that message by poking at Obama's recent suggestion that it is hard to change Washington from the inside without mobilizing public pressure on Congress from the outside.
"Why do we send presidents to the White House in the first place?" Ryan asked. "We send presidents to change and fix the mess in Washington, and if this president has admitted that he can't change Washington, then you know what, we need to change presidents."
Obama is hitting back by portraying Romney as an insider beholden to partisan and corporate interests. Vice president Biden seconded the president on Saturday, saying to an audience of teamsters it was because of unions that the US has a strong middle class. Biden also accused Romney and Ryan of "doubling down on everything that caused the economic crisis in the first place".
Obama entered the weekend with polls showing him in a near tie with Romney nationally. But the latest Wall Street Journal/NBC News/Marist poll shows the president with leads among likely voters of 8% in Iowa and 5% in Colorado and Wisconsin, some of the most competitive states. Polls published earlier this week pointed to leads for Obama in closely contested Virginia and Ohio.
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