President Barack Obama is moving to shore up support in a key US state while he and Republican nominee Mitt Romney spar over how to transform a bitterly divided political culture and how to best ensure the financial and health security of older Americans.
With the candidates' first debate in less than two weeks, the two men and their campaigns have begun to engage at an accelerated pace, giving any rival's phrase outsize importance and freshly dissecting old policy fights.
Mr Obama is due in Wisconsin, a state that his campaign had considered safely on his side, but which Obama aides seem eager to fortify in case Mr Romney's running mate, Wisconsin native and congressman Paul Ryan, can erode the president's support.
Mr Romney, faced with second-guessing within his own party over his strategy, has been in California to raise money, eager to recover his fundraising advantage. Last month, for the first time, Obama and the Democratic Party raised more money than Romney and the Republicans.
Mr Romney opened a new line of attack against Mr Obama, casting the president as a failed agent of change. Mr Obama countered by portraying Mr Romney as an insider beholden to partisan and corporate interests.
At the same time, Mr Romney tried to put an end to an old controversy by releasing his 2011 tax returns and his past tax rates, reinforcing his place as one of the wealthiest candidates ever to seek the presidency. Mr Obama sought to gain an edge with older voters and near-retirement baby boomers by renewing his criticism of Mr Romney's Medicare proposals.
Mr Romney earned almost 13.7 million US dollars (£8.4 million) last year and paid more than 1.9 million US dollars (£1.17 million) in taxes - an effective tax rate of 14.1%. By comparison, President Barack Obama's tax return shows he earned nearly 790,000 US dollars (£487,000) last year and paid an effective tax rate of almost 21%.
In the US, wages are taxed at a higher rate than investments, which make up the bulk of Mr Romney's income.
The tax rate Mr Romney paid last year is lower than that of millions of middle-income Americans, but it is more than he had to pay, since he limited tax deductions on the more than four million US dollars he and his wife gave to charity.
Mr Obama enters the weekend with polls showing him in a near tie with Mr Romney nationally. But a new Wall Street Journal/NBC News/Marist Poll shows the president with leads among likely voters in three key states - Iowa, Colorado and Wisconsin.