DES MOINES, Iowa — Hillary Clinton was always expected to get a late-campaign enthusiasm boost from the White House. The surprise is that it’s not coming from the president.

On a star-studded team of campaign surrogates — including President Barack Obama — the most valuable player of 2016 is undoubtedly first lady Michelle Obama.

During a divisive political year, the hugely popular first lady has wowed voters with her powerful rhetoric. And she can be the emotional center to a campaign whose candidate is not known for projecting warmth.