…but the most costly defection was that of Sen. Robert Menendez (N.J.), a member of the Democratic leadership, in protest of a little-noticed Cuba provision that would ease U.S. rules on travel and imports to the communist-led island.

The Menendez rebellion was a jolt of political reality for Reid, House Speaker Nancy Pelosi (D-Calif.) and Obama, signaling that the solidarity of the stimulus debate is fading as Democratic lawmakers are starting to read the fine print of the bills they will wrestle with in the coming weeks and months, and not always liking what they see.

Menendez knew that his hard-line approach to Cuba was a minority view within his party, and that it was at odds with Obama's approach. But he did not expect to discover a significant policy change embedded in the text on an appropriations bill. His policy aides came across the language when the legislation was posted on a congressional Web site.

"The process by which these changes have been forced upon this body is so deeply offensive to me, and so deeply undemocratic, that it puts the omnibus appropriations package in jeopardy, in spite of all the other tremendously important funding that this bill would provide," the enraged son of Cuban immigrants said last week on the Senate floor. Menendez even slapped a hold on a pair of Obama nominees to draw attention to the issue.

…Menendez has pointed out that, had the bill sought significant changes in U.S. policy toward Iran or Venezuela, lawmakers would revolt. "What's the difference with Cuba?" said Menendez spokesman Afshin Mohamadi.