"McCain endorsement of Romney," Michael Reagan tweeted, "is the kiss of death."
The endorsement will signal there is "no way now for Mitt to win" in South Carolina or Florida, he wrote, a scenario that does not appear to disappoint Reagan.
"Go conservatives," Reagan concluded.
Reagan congratulated former US Sen. Rick Santorum for his showing in Iowan, and praised Santorum's speech after the Iowa Caucus ended, calling it "Reaganesque" and saying "Bravo!"
Reagan was hoping Romney would have a poor showing, leading to opportunities for Santorum and former Speaker of the House Newt Gingrich.
His pre-caucus assessment of US Rep. Michele Bachmann was not as upbeat, saying "Bachman needs to go home and run for her congessional seat."
Reagan initially toyed with a race this year against incument US Sen. Dianne Feinstein, but dropped the idea.
He is the author of three books, "On the Outside Looking In," "The Common Sense of An Uncommon Man: The Wit, Wisdom and Eternal Optimism of Ronald Reagan" and "Twice Adopted."
Reagan is a radio talk host and president of the Reagan Legacy Foundation.
His official website is located at http://www.reagan.com/.
His Twitter account is @ReaganWorld.
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