Gary Levin

USA TODAY

It was Tina Fey's idea to enlist her 30 Rock co-star Alec Baldwin to play Donald Trump on several episodes of NBC's Saturday Night Live, starting with this weekend's 42nd-season opener (11:30 p.m. ET/PT).

SNL's executive producer Lorne Michaels was talking to Fey (an alum of SNL) over the summer, and "She said, 'You know who would be a great Trump is Alec!' " he recalls. "I talked to Alec, who was finishing a movie, he was getting ready to have a baby — it couldn't have been worse timing. But, slowly, the idea grew on me. People on the show liked it, and I thought he'd be great with Kate" McKinnon, who plays Hillary Clinton.

"And I thought, well, he's Alec," who holds the record as 16-time host of the late-night institution and might offer a fresh take on the Republican presidential candidate and NBC's TheApprentice star, at least until the election.

At first, Michaels says, Baldwin was uncertain: "He said, 'I'm not sure I have a Trump,' and I said, 'Yeah, you do.' "

Darrell Hammond, who begins his third season as the show's announcer, will give up the role, but is expected to continue playing Bill Clinton.

"I knew that I wanted to shake it up," Michaels says. "It was nothing to do with Darrell, because he's obviously great at it." But "just as Darrell took over from Phil Hartman doing Bill Clinton, these things have to change. I don't know how many people have played Hillary Clinton."

Other changes include the addition of three new "featured players" to the cast: Mikey Day (a writer on the show since 2013), Melissa Villaseñor, (the show's first Latina) and Chicago comedian Alex Moffat. Michael Che, Pete Davidson and Leslie Jones have been bumped up to full repertory cast members. And Taran Killam and Jay Pharoah were let go, with a year remaining on their contracts.

"I think they were great, and they did wonderful work when they were with us," Michaels says of Killam and Pharoah. "They served the show well, and are two people I really care about." But "change is the lifeblood of the show; it always has been. And you have to keep bringing new people in. Hopefully it's for the best. I'm not worried about either of them going on to success." (Both will star in Showtime comedy pilots.)

Margot Robbie will host this weekend's opener, with The Weeknd as musical guest. Next week Hamilton creator and star Lin-Manuel Miranda will host, with Twenty One Pilots.