Senator Edward Kennedy's death early on Wednesday morning, though expected, has provoked an incredible outpouring of sympathy from both sides of the political spectrum in the United States and from leaders around the world. Their reaction to Ted Kennedy's death is proof positive of the significance of his life.

As someone born, raised and educated in the Boston area, whose family has been active in Massachusetts Democratic Party politics since emigrating from the west of Ireland, Ted Kennedy was always the central figure on my political radar screen.

One thing that has escaped notice in the mainstream media reports of his death is Kennedy's often fraught relationship with the Boston Irish – those of us who hail from the city's ethnic neighbourhoods or close-in suburbs and still can't pronounce the letter "r". Many of us never forgave his questionable behaviour at Chappaquiddick, or his endorsement of forced bussing in a misguided effort to desegregate Boston's public schools, or his leftward lurch on social issues, or his support for race-based affirmative action programmes that effectively discriminated against working-class ethnic Catholics.

Despite these profound disagreements, most of the Boston Irish still supported him at the ballot box. My uncle, former congressman Brian Donnelly, served with Kennedy for 14 years in the senate and, like many others, marvelled at his capacity as a legislator and was especially grateful for his help in shepherding the Donnelly visa legislation through the United States senate.

Because of Kennedy's well-honed skills, his surname and the unrivalled abilities of his legislative staff, he could single-handedly get things done in the senate, a hyper-deliberative body that typically moves at glacial speed. He used this power to benefit the marginalised in American society, our home state and sometimes, like any politician, to further his own ends. My family felt this particularly acutely in 1993, when Kennedy "persuaded" then president Bill Clinton to appoint his sister, Jean Kennedy Smith, United States ambassador to Ireland, even though Clinton has explicitly promised the job to my Uncle Brian.

While we were disappointed, Kennedy clearly had a plan in mind when he undertook to get his sister installed in the post. Once and for all, he wanted to help forge a lasting peace in Northern Ireland and he was ready to put himself out on a limb for it with little or nothing to be gained politically. He got Gerry Adams into the United States and the ball got rolling from there.

He stayed closely involved in the peace process, actively sought to encourage American investment in Ireland, fostered stronger links between our two countries and has always been a champion for the undocumented Irish in the United States. For that, Ireland and Irish America owe Ted Kennedy a debt of gratitude that can never be repaid.

But can the face of Irish America ever be replaced? Who will Ireland turn to now? Political manoeuvring to replace Kennedy will soon begin. In his dying days, he asked that the Massachusetts legislature change the existing law and allow the governor to appoint a temporary successor before a special election is held in five months to replace him. This is to ensure the state has two votes when the senate debates controversial healthcare legislation that would extend coverage to some 50 million uninsured Americans. It was the cause that most animated his public life and it's highly likely the Massachusetts legislature will accede to his last wish.

There has been much speculation that either his wife, Victoria Reggie Kennedy, or his nephew, former congressman Joseph Kennedy, will be appointed to fill the short-term vacancy. Furthermore, it's been mooted that one or the other will be a candidate to fill the vacancy on a long-term basis when the election is held in five months.

Both, however, have been reticent on the topic. Kennedy's wife has always dismissed such speculation out of hand and his nephew has been plagued by scandal in the past and is said to face strenuous opposition from his wife to any return to the political foray. While either could emerge as either a short- or long-term replacement, my suspicion is neither will. At any rate, whoever fills the vacancy will have very big shoes to fill and will lack Kennedy's national and international stature.

It is likely that the Kennedy political dynasty – congressman Patrick Kennedy of Rhode Island is the only current office-holder – will have to be resuscitated by the next generation if it is to survive.

Is there anyone else? There are Irish-American congressmen who represent heavily Irish-American districts and are deeply committed to Irish issues – for instance, Richard Neal and Stephen Lynch of Massachusetts, Joe Crowley of New York – but they lack a national profile. My hope is that they find strength in numbers and make themselves known as the new first port of call for the Irish government.

One person to watch outside the congress is Maryland governor Martin O'Malley. He is a very smart, capable and ambitious politician with strong family connections in the west of Ireland and an abiding passion for this country.

He supported Hillary Clinton in the Democratic primary last year, but quickly mended fences with Barack Obama and is one of his unofficial coterie
of advisers on Irish issues. O'Malley is said to have national ambitions and may be the next great hope for Ireland and Irish America.

While these and many other thoughts run through my mind in the wake of Ted Kennedy's passing, it becomes ever more difficult to conceive of life back in Boston without him. May he rest in peace.

Larry Donnelly, a Boston attorney and Democrat, is a law lecturer at NUI Galway