Hopes for Republican presidents down the road would be slim if Democratic nominee Hillary Clinton were to defeat Donald Trump , conservative commentator and best-selling author Ann Coulter told CNBC on Tuesday.

Coulter said on "Squawk Box" a Clinton presidency would usher in amnesty for undocumented immigrants and open borders, stacking the deck with future voters.

"There will be no hope for any Republican winning another election. There's no point to what I do, what talk radio hosts do, what Fox News does," Coulter said. "Nobody goes to the game if you can't win."

But Coulter does not believe Clinton will prevail, despite leading in the polls with just 76 days until the election. Coulter predicted: "The polls will get closer because [Trump] is going to win."

Coulter's new book — "In Trump We Trust: E Pluribus Awesome," which went on sale Tuesday — aims to explain the engine that led to the rise of Trump and why voters should get on board.

"It is utterly unfair the way the media is treating Donald Trump," she argued, saying that Trump's off-the-cuff tweets and rallies with tens of thousands of people are the only ways he can talk directly to voters without a liberal media filter.

Trump does a better job staying on message when he uses a teleprompter, Coulter admitted, praising the policy speeches the Republican nominee has been delivering in the past couple weeks.