"The fact is that today's 'Republican' Party is one with which I am totally unfamiliar. To me, the word 'Republican' has always been synonymous with the word 'responsibility,' which has meant limiting our governmental obligations to those we can afford in human and financial terms.

"Today's whopping budget deficit of some $440 billion does not meet that criterion," Eisenhower wrote.

Eisenhower, a former American ambassador to Belgium and an author, was registered as a member of the GOP for 50 years -- until the Bush administration's decision to invade Iraq "as a maverick," he wrote.

"Recent developments indicate that the current Republican Party leadership has confused confident leadership with hubris and arrogance," Eisenhower wrote.

He went on to question the Republican Party's willingness to protect individual freedoms and privacy. "Of course we must fight terrorism, but have we irresponsibly gone overboard in doing so?" he asked.

The Republican leadership's tax code "heads us in the direction of a society of very rich and very poor," Eisenhower wrote. No longer are Republicans concerned for the middle class and small business, he said.