President Joe Biden is ahead of Donald Trump in six out of seven key swing states, with at least two by significant margins, according to an opinion poll by Bloomberg News/Morning Consult. The shift occurred after five months of Trump’s mainly leading position and followed the president’s State of the Nation address, which rallied Democrats and seemingly eased concerns about Biden’s age. The change was significant in Wisconsin, where Biden leads Trump by one point after trailing him by four points in February, and in Pennsylvania, where the candidates are tied after Trump led by six points las…