But it is not Gyllenhaal's account.
The Twitter account is not verified by Twitter, and the bio includes a line that makes it clear it is not the actor's account: "This is my fansite, Not here to be a Celebrity."
The powerful conservative news aggregator Drudge Report linked to the tweet under the headline: "Actor Jake Gyllenhaal endorses Romney," which attracted media attention and re-tweets.
Tagg Romney, the eldest son of Mitt Romney, also got fooled and tweeted as much.
Jumped the gun, fake @jake_gyllenhaal— Tagg Romney (@tromney) October 16, 2012
The account has since been suspended by Twitter, either because it is a fake or because of the high volume of traffic.
The three tweets read:
If Obama Has All These Answers Of How To Save Our Country, Why Hasnt He Implemented These In The Last Four Years ... As A Democrat, I'll say it now, I endorse Mitt Romney For President Of The United States #MyVoteIsMade ... Obama doesnt listen to Romney at all in any debate, Romney's saying I dont believe that, yet Obama insists time and again he does #Stupdity
Gyllenhaal is a politically active Democrat. His sister Maggie Gyllenhaal, the star of "Won't Back Down," recently joked to NBC's "Today" show that her family identifies by their progressive causes.
"I wouldn't be allowed to come home for Thanksgiving if I made an anti-union movie," she said.