Americans are growing increasingly more frustrated with President Barack Obama’s handling of the economy and only 3 in 10 say they are certain they will vote to re-elect him in 2012, a new poll finds. Just 23 percent of those surveyed for a Bloomberg News poll released Wednesday say they are hopeful about the economy because they see signs of improvement, while 25 percent say they are fearful things are getting worse and 51 percent are cautious because nothing seems to be happening. Those signs of economic pessimism aren’t helping Obama’s reelection bid. Sixty-one percent of Americans say they believe...