A man cleans up broken glass after a bullet was fired into a Denver campaign headquarters of President Barack Obama.<br/> <br />Although staff were in the building at the time of the Friday shooting, no one was hurt.<br/> <br />Denver police are looking at surveillance footage to possibly identify a passing vehicle.<br/> <br />The shooting comes as the presidential race enters its last few weeks.<br/> <br />Obama, who struggled during the first debate, is neck and neck with his Republican opponent.<br/> <br />But Vice President Joe Biden's energetic performance in his debate has reinvigorated liberals.<br/> <br />Republican running mates Mitt Romney and Paul Ryan are banking on the United States' embattled economy to boost their numbers ahead of the November polls.
