Courtesy Palgrave Macmillan (Courtesy Palgrave Macmillan)

Among the 100 senators are a few who might harbor presidential ambitions (we’re lookin’ at you, Sens. Rubio, Cruz, Paul, Warner, Warren, et al).

A new book by journalist John Shaw, “JFK in the Senate: Pathway to the Presidency,” examines an often overlooked chapter in the life of President John F. Kennedy — and offers a playbook that those eyeing the other end of Pennsylvania Avenue might find useful. Here are five lessons that a would-be presidential candidates now serving in the Senate might draw from JFK’s example.

1) Don’t wait for gray hair. Running for president doesn’t get easier the longer you serve in the Senate. JFK was 43 when he took office. And though he was dinged for being a young man in a hurry (a New York Times headline from 1958 was “Kennedy: Good Man Moving Too Fast,” Shaw notes), he didn’t listen to the criticism.

2) Use the Senate. The upper chamber can be a great platform for a presidential candidate, and JFK used his time in the Senate as a “policy training ground and a political launching pad,” Shaw writes. He worked on his political skills, significantly improving his oratory, in particular. “I can’t afford to sound just like any other senator,” he once said.

3) Don’t be an insider. Don’t get too involved in the fickle institution’s day-to-day management. It takes too much time, and you get blamed when good ideas get stalled in the Senate (and they always will). Of Kennedy’s eight years in the Senate, fellow senator Hubert Humphrey observed: “John Kennedy never made his life in the Senate, as such. He worked in the Senate.”

4) Don’t look back. An ambivalent, conflicted senator never wins the White House. Forget your Senate attendance record.

5) Enjoy it. JFK often said that “the margin is awfully small’ between winners and losers in politics, “like it is in life.” He also said running for president can be a blast. “How could it be more fascinating to run for president under the obstacles and hurdles that are before me?” he wondered in January 1960.