BALTIMORE — Rob Manfred, a high-ranking executive for Major League Baseball, settled into his first-class seat on Amtrak’s 2 p.m. Acela train on Tuesday, heading from New York to Baltimore.

He opened a copy of Major League Baseball’s constitution. Manfred had a two-hour ride ahead, and he wanted to be armed, he said, for what he would face on the other end. His fate as a baseball executive was on the line.

Two days later, after several rounds of presentations and deliberations — and no small amount of back-room lobbying and debate — Manfred’s preparations were rewarded. He was chosen Thursday by the league’s owners to succeed Bud Selig as commissioner, one of the most powerful positions in sports.

Manfred was confirmed as the sport’s 10th commissioner after six rounds of voting by baseball’s 30 owners, who convened in a closed-door ballroom in downtown Baltimore until at least 23 of them — or more than three-quarters — were in agreement.