Definition of "shoo-in"

Little Pete was a member of the delegation that were in on the "shoo" in the third race. He had several commissioners placing his coin on Model. If the race was to have been a "shoo-in" for Model, there must have been one or two owners that were not in on the deal.

1895, “Pointers from the Paddock”, in The San Francisco Call‎

Most of the "regulars" are deeply suspicious of all steeplechase races of late years, and, whenever the favorite falls at one of the obstacles and a long priced leaper wins the race, they loudly call the race a "shoo-in" (a fixed affair, that is, in which the steeplechase racers have arranged to drop to the rear of the "meant" jumper and "shoo" him to the wire, they previously, of course, having got their money down on the horse thus generously treated).

1910, “Vernacular of the Race Track”, in New-York Tribune‎

[it was] wondered whether Chris Chenery's Virginia flyer would be a shoo-in for the Belmont Stakes […]

1950, Baltimore Sun

Participation in primaries was often more important than in the general election because the Democratic Party nominee was a shoo-in for success in the general election.

2007, Governors Speak, by Jack D. Fleer, page 47

Despite this heady mix, Milei is broadly considered the undisputed shoo-in president appealing particularly to young underprivileged men.

2023 August 27, Uki Goñi, “The ‘false prophet’ v the pope: Argentina faces clash of ideologies in election”, in The Observer‎