Natalie DiBlasio

USA TODAY

The breakfast war has turned to Twitter.

As Taco Bell launches into the $50 billion fast-food breakfast market, competitor McDonald's is not keeping quiet.

Late Friday night, McDonald's tweeted a picture of Ronald McDonald crouching down to pet a Chihuahua with the words "Imitation is the sincerest form of flattery."

The battle goes both ways. Taco Bell gathered 25 men named Ronald McDonald from all over the country and featured them in their newest ad. The men all introduce themselves and express their love for Taco Bell's new breakfast.

McDonald's replied with a tweet: "Breaking! Mayor McCheese confirms: Ronald, in fact, still prefers McDonald's."

McDonald's also announced another competitive move: free cups of McCafe coffee during regular breakfast hours from March 31 through April 13.

Taco Bell's 14 breakfast offerings rolled out on March 27.

Among the options: the Waffle Taco (warm waffle wrapped around sausage patty or bacon with eggs, cheese and syrup); A.M. Crunchwrap (scrambled eggs, hash browns, cheese and bacon or sausage in a flour tortilla); Cinnabon Delights (poppable Cinnabon treats).

Right now, McDonald's is the industry leader at fast-food breakfast with about a 25% market share.

Contributing: Bruce Horovitz