Some of the issues that Republicans are beginning to raise paint a picture of what the fall election strategy against Mr. Obama might look like. Some are traditional, using Mr. Obama’s support for withdrawing the troops from Iraq to portray him as weak on national security and his opposition to suspending the federal gas tax this summer to show him as a tax-and-spend Democrat.

A rotating banner at the top of the Republican Party home page asks, “Why does Barack Obama want to increase taxes again and drive up the cost of gasoline on Americans?” It also ties him to the liberal group MoveOn.org, and features an advertisement called “Barack Obama’s Gas Tax Hypocrisy,” noting that while he now opposes suspending the gas tax, he once supported a similar measure when he was an Illinois lawmaker.

“Barack Obama just doesn’t get it,” a narrator intones. “Does he understand our economy, and what American families and businesses need? Barack Obama. Out of touch. Not ready to be president.”

Another line of attack seems to be squarely directed at independent and swing voters, whom both the McCain and Obama campaigns have been courting. The McCain campaign has argued that Mr. Obama lacks a record of bipartisan achievement to back up his calls for healing partisan rifts in Washington and getting things done. That issue was underscored this week when, in a speech on the judiciary, Mr. McCain contrasted his own willingness to vote for President Bill Clinton’s judicial nominees with Mr. Obama’s votes against President Bush’s judicial nominees, including Chief Justice John G. Roberts Jr.

Image Barack Obama and his wife, Michelle, at a rally Tuesday night in Raleigh, N.C. Mr. Obama spent Wednesday at home in Chicago. Credit... Doug Mills/The New York Times

“Senator Obama in particular likes to talk up his background as a lecturer on law, and also as someone who can work across the aisle to get things done,” Mr. McCain said. “But when Judge Roberts was nominated, it seemed to bring out more the lecturer in Senator Obama than it did the guy who can get things done. He went right along with the partisan crowd, and was among the 22 senators to vote against this highly qualified nominee.”