Ken Howard in According to Tip at the New Repertory Theater in Watertown, Mass.

BOSton globe / YOON S. BYUN

Ken Howard knows playing Tip O’Neill, a god of gods in Boston’s political firmament, carries the risk of doom.

“Am I intimidated?” he asks. “No. I think, though, this is the first time in a long, long time that I’m a little scared. It’s a daunting task.”

Howard, all 6 feet 5 of him, will personify the longtime Speaker of the House in the one-man show According to Tip, which makes its world premiere starting today at New Repertory Theatre in Watertown, just north of Boston. He knows that his core audience — pols, press, and Bostonians of a certain age, wise guys of all stripes from City Hall and Beacon Hill — will be a brutal audience.

They will weigh his every word. They will listen for tone. They will look for their truth in his Tip O’Neill, his rhythms and mannerisms.

“This is not an impersonation,” cautions Howard over a late hotel breakfast. “Rich Little or Frank Gorshin would do this differently,” he says of the two impressionists. “That’s about seeing how skillfully someone can impersonate someone else. I want to capture the heart and soul of Tip, his presence.”

Howard, 64, has a good shot at taming this crowd because the 112-page script is written by Dick Flavin, a close observer of Boston’s political wars, a member of the Irish tribe, and a veteran raconteur. Flavin, a vibrant 71, has been a political humorist since the Big Bang and served as Mayor Kevin White’s press secretary for a spell.

Flavin takes us on a gentle ride through O’Neill’s life, from his youth near Barry’s Corner through state politics to Congress and on into retirement. Along the way, he does yeoman service honoring the man’s humor and penchant for song. The show contained six tunes at the start of rehearsals, including the fabulous “The Irish Were Egyptians Long Ago,” which begins: “It must have been the Irish who built the pyramids.”

Flavin couldn’t resist a man like O’Neill, willing to stake his reputation for his beliefs. “I’ve always had a soft spot for pols when they put their identities on the line,” he says over coffee. He also has been sensitive to the O’Neill family and gained its approval for the play.

The play itself will rise or fall on the balance it strikes between the “entertainment” both Flavin and Howard say they envision and the edge producing director Rick Lombardo wants in it to avoid delivering a big wet kiss.

“It will only be full if we get into his failures and disappointments,” says Lombardo. “It can’t just be an entertainment. What drew me to the play for the Rep is that it speaks to this transformation in American politics. Tip at the end of his career was a little bit of a fish out of water. Ultimately, this is an homage to a giant of a figure in American politics, but it would be a disservice if we only idealize the man.”

Is there a dark side to O’Neill? “The dark side is the family,” says Howard. “He was always haunted that he didn’t bring his family with him to Washington.” Flavin includes O’Neill’s guilt over this and the difficult relationship he had with a son, Michael, who died from alcohol and drugs.

If According to Tip flies, Flavin plans to take it first to Dublin in the fall, followed perhaps by Washington and off-Broadway in New York.