After challenging John McCain on foreign policy, Democrat Barack Obama fired off a new broadside Sunday as he linked the likely Republican nominee with President George W. Bush's unpopular economic policies as he tested general election strategies. Obama was campaigning ahead of Tuesday's primaries in Oregon and Kentucky which should leave him less than 100 delegates away from reaching the total 2,026 needed to secure his party's nomination after an epic battle with Hillary Rodham Clinton. Obama has begun casting himself as the inevitable nominee and using his time to distinguish himself from McCain as he pivots toward the November election campaign. He has scheduled appearances later this week in Iowa and Florida, two key swing states that have already held their primaries. Obama, who is bidding to be the first black US president, has also started tailoring his message to voting blocs like senior citizens that favored Clinton in their nomination contest and will be important in the November election. On Sunday, Obama tried to undermine McCain's appeal to fellow senior citizens by turning to a bedrock, pocketbook issue as he spoke to about 130 people at an assisted living facility in Gresham, Oregon. He said the Republican candidate would threaten the Social Security retirement benefits that they depend on because he supports Bush's policy of privatizing the program.