Who's the boss, baby?

ALEC Baldwin has a knack for playing leaders, from slick TV executive Jack Donaghy in hit sitcom 30 Rock, to his hilarious impersonations of US President Donald Trump on Saturday Night Live. In the flesh, you can see why; he's a suitably commanding presence, with his sharply-tailored suit and deep, distinctive voice. At home in New York, however, with his yoga instructor wife Hilaria and their three small children, Baldwin insists he's far from the boss.

"I'm like the lowest life form," jokes the actor, who has just turned 59 and also has a grown-up daughter, Ireland, with ex-wife Kim Basinger. "I think if I disappeared one day, my wife and kids wouldn't even notice - until it was time to put gas in the car in the freezing cold."

He's back in charge in his latest film, but this time there's a twist: he's a boss who also happens to be a baby. The Boss Baby centres around seven-year-old Tim, who is upset to find a rival on the scene in the form of a new little sibling (voiced by Baldwin), who happens to be suited, booted and carrying a briefcase. It transpires that Boss Baby is actually a spy on a secret mission, who needs Tim's help to thwart a dastardly plot involving puppies and babies.

It's a bit of a leap from his usual roles, but Baldwin could relate to the DreamWorks film's depiction of sibling rivalry, having witnessed it first-hand when his son Rafael was born. "My wife and I have a daughter, Carmen, who is three, and before my son was born she was the princess and was just adored and catered to by everybody. Then my son came along - and he was the first son, so I just flipped out," says the star, who has since welcomed a second son, Leonardo, into the world.

"At this time, Carmen was two years old. She would stare at him thinking, 'Something's got to change around here. You know we have to fix this!' So for my daughter, there was a process to be able to accept her little brother. "When she finally gave him a kiss, we all cried," he recalls. "We thought this day would never come."

One of six - his three younger brothers, Daniel, William and Stephen, all became actors, and he also has two sisters - Baldwin must also have experienced some sibling rivalry in his time?

"I guess all siblings have a rivalry, in so far as you live in those concentrated quarters with other people your whole life, when you're becoming who you're going to become. You are your most insecure and you don't know who you are, what you want; you're your most uncertain about what's going to happen to you in the world. But I never felt my brothers were my rivals, because I was the oldest," he adds with a smile. "I always felt that I was the dauphin."

Overall, The Boss Baby has "a wonderful heart inside it", as Baldwin's character is eventually won over by the prospect of being part of the family.

"Plus there are a lot of crazy scenes and wild action, because in animation, you can do anything."

It's his recent performances as Trump, however, that have really got people talking (a young fan at the Boss Baby New York premiere even persuaded Baldwin to recreate the impersonation on the red carpet). His note-perfect, fired-up portrayals of the controversial president on US TV show Saturday Night Live, complete with orange glow and blond wig, have racked up millions of views online. They also seem to have riled the real Trump, who has taken to Twitter to complain that "the Baldwin impersonation just can't get any worse".

"The key to it is the writing. You could do the most deft, spot-on impersonation of Trump, and it wouldn't matter if you didn't have good writing," says Baldwin. "And I don't do the most spot-on impersonation of Trump, I do my version of Trump, kind of a caricature of a more malicious Trump. I suppose if I spent some time, I might be able to refine my impersonation of him. But in the meantime the lines we have, we're quoting Trump almost verbatim, so therefore we couldn't help but make it a little angry."

The actor, a Democrat who has reportedly previously entertained thoughts of running for mayor of New York, doesn't think the Trump skits will continue for much longer, however. It's "exhausting", for a start, plus he doesn't know whether there'll be an appetite for it for much longer.

"If everything stays the same in this country as it is now, I don't think people are going to be in the mood to laugh about it this September," he says, looking serious. "As we round the corner to the one-year anniversary of the election, I think people might be in a completely different frame of mind. We'll see if this is actually the first satire-resistant Presidency..."

• The Boss Baby is in cinemas now.