Over the last 10 days, Barack Obama has kept himself fairly out of sight while spending a family vacation at Martha’s Vineyard. But he is about to return to his party’s political scene with a bang as he hopes to push back against a groundswell of Republican support this election season. Which is just fine with the Republicans. “He makes our argument for us,’’ said a spokesman for the Republican National Committee. “When he talked about jobs and the economy, voters know the stock market is down, the housing market is falling, and the job market has not recovered.’’ The Democrats, however, are still convinced that the message of hope and change that saw the president swept into office two years ago can help, and that he can convince voters that economic recovery is a slow, gradual process. “He’s going to be hustling on the road until the November election and he’ll be relishing the opportunity,” said Tim Kaine, chairman of the Democratic National Committee.