After sailing through two presidential elections by comfortable margins, President Barack Obama finds himself bogged down only six months into his second term.

His administration is fending off attacks on multiple fronts, including delays rolling out his signature health care plan, Internal Revenue Service practices, efforts to overhaul the immigration system and the National Security Agency's intelligence-gathering techniques.

Jonathan Alter's book, "The Center Holds: Obama and His Enemies," about the 2012 election, offers some valuable insights into why this master campaigner finds the job of president more challenging than running for office.

Alter writes of his fascination with "the paradox of a man who succeeds so spectacularly at a profession he often dislikes. He is missing the schmooze gene that is standard equipment for people in politics." And he notes Obama's missed opportunities, including his failure to pivot quickly back to the economy after his health care plan passed.

Alter looks at the long list of Obama's "enemies" who opposed his re-election and have blocked much of his agenda.He examines the rise of the tea party, which he describes as "best understood as a loosely organized collection of several hundred tiny groups connected mostly by websites and social media." That group develops into a powerful political force that successfully blocked much of Obama's strategy for the early part of his presidency.