Washington, DC CNN — President Joe Biden is sharpening his attacks against former President Donald Trump – in public and, even more so, in private – as recent polls show warning signs for the Democrat in their possible rematch next fall. Biden personally wanted to speak out this week after Trump described his political opponents as “vermin,” a senior adviser said, landing on a private California fundraiser as the venue. “There’s a lot of reasons to be against Donald Trump. But damn, he shouldn’t be president,” the president bluntly declared. Armed with a teleprompter, he said Trump’s words amounted to...