Donald Trump fears longshot Republican opponent Vivek Ramaswamy will cut into a pivotal voter bloc for the former president, according to a new report. Tom LoBianco, political reporter for 24sight and biographer of former Vice President Mike Pence, spoke with Trump insiders about campaign worries ahead of the Iowa Caucus. “Simmering just beneath the surface has been a worry among Trump and some on his team that Ramaswamy will eat into Trump’s margin of victory Monday night, particularly among a key subset of voters,” LoBianco writes. “Young men.” READ MORE: Busted: Vivek Ramaswamy campaign too…