A soon-to-be-published e-book discusses how personal the presidential race has become.

When President Obama talked about Mitt Romney in recent months, "aides picked up a level of anger he never had for (Hillary) Clinton or (John) McCain," writes Politico's Glenn Thrush in Obama's Last Stand, which will be out on Aug. 20.

Thrush notes that Obama "began campaign preparations feeling neutral about Romney, but like the former governor's GOP opponents in 2008 and 2012, he quickly developed a genuine disdain for the man," according to excerpts released by Politico.

Of course, we suspect that Romney's views of Obama may be somewhat similar.

Obama's Last Stand is the latest in a series of e-books on the campaign produced by Politico.

Writes Thrush of the president's anti-Romney views: