BOSTON >> When New York businessman Donald Trump roared to a decisive victory in Massachusetts' Republican presidential primary he seemed on his way to the GOP nomination.
Since then, Trump's path has narrowed, raising the possibility of a contested convention when the party meets in Cleveland in July to pick its presidential nominee.
That scenario has cast a spotlight on the otherwise arcane process of choosing delegates to the convention — a practice typically of interest only to political obsessives and party stalwarts.
Why does the selection of delegates matter so much this year?
In a typical year, when the selection of the presidential nominee is decided well before the actual convention, the naming of delegates has no real impact.
But this year had been far from typical for Republicans.
Trump is currently leading in the delegate race to the chagrin of many party elders — including former Massachusetts Gov. Mitt Romney — who fear he's unqualified to be president, isn't a true conservative and has little chance of beating the Democratic nominee — whether that's Hillary Clinton or Bernie Sanders.
Their one hope is that Trump fails to collect the 1,237 delegates needed to win outright, prompting a floor fight after a first ballot.
What does that mean for Massachusetts delegates?
Massachusetts has been allotted 42 convention delegates.
Of those, 22 are bound to Trump on the first vote, given that he captured about 49 percent of the primary vote.
That left eight delegates for John Kasich, eight for Marco Rubio and four for Ted Cruz. Since Rubio has suspended his campaign rather than formally withdrawing, his eight delegates are also bound to him on the first vote.
What happens after the first round of voting?
This is where things get interesting.
If none of the candidates reach the magic number of 1,237, delegates are free to change their vote.
That means all 42 delegates from Massachusetts can cast ballots for anyone they want. The 22 bound for Trump can bolt for other candidates if they want.
There's also no requirement that a delegate declare his second or third round preference ahead of time — meaning their selection of a potential nominee is a matter of their personal preference.
So how are the 42 delegates selected?
The majority of the delegates — 27 — will be elected at nine congressional district caucuses that will be held across the state on April 30. Each caucus will elect three delegates and three alternate delegates.
Another 12 at-large delegates will be elected by the Massachusetts Republican State Committee on May 25.
The final three delegates are members of the Republican National Committee from Massachusetts — the chair of the state party and the national committeeman and committeewoman.
What does that mean for ordinary GOP voters in Massachusetts?
With the possibility of a contested convention looming, the last, best way for Republican voters to have a say in the selection of their party's presidential nominee is to attend one of the nine caucuses April 30.
The caucuses are open to any voter registered as a Republican by Feb. 10, 2016, the same registration deadline for the presidential primary
Although prospective delegates don't have to announce how they might vote on a second or third ballot, there's nothing stopping those attending the caucuses from asking.