A Behind-The-Scenes Peek Inside The Mitch McConnell Legacy Vault

— -- He was an intern on Capitol Hill in the summer of 1963, a boy from Kentucky, when the dream was first planted in his mind.

Mitch McConnell didn't aspire to be president. His ambition: becoming the majority leader of the U.S. Senate.

A half-century and nine presidents later, McConnell’s quest will come true on Thursday, a week after Republicans captured control of the Senate.

But who is Addison Mitchell “Mitch” McConnell Jr?

From a childhood affliction with polio, to his audacious first bid for the Senate in 1984, the stages of his life are on display at the McConnell Center at the University of Louisville. ABC News recently toured the gallery and archives, which offer a glimpse into McConnell’s life: From his immaculate boyhood handwriting to his bare-knuckle political campaigns, rising from his first post as Jefferson County Judge Executive to become the majority leader of the U.S. Senate.

McConnell, 72, has taken a path of precision, patience and perseverance to the Senate majority leader’s office. He will preside over a cantankerous GOP caucus and a skeptical conservative base as he emerges as the most powerful Republican in Washington. Here, he’s always been more feared than beloved -- and that’s just among Republicans.

But after winning re-election to a sixth term by a 16-point margin – in a race Democrats invested tens of millions and made him their top target – McConnell takes on his new post with a confident swagger. On Wednesday, he smiled broadly as he welcomed the new Republican class to his office suite in the Capitol looking out on the National Mall.

“We're here to make the place function again,” McConnell said, “and to begin to make progress for the American people.”