Republicans call it a government cover-up similar to what forced Richard Nixon to resign. Democrats call it a right-wing conspiracy theory.

The fallout from the September 11, 2012, terrorist attack in Benghazi, Libya, that killed four Americans continues more than 19 months later, with further details this week that raised questions about how the Obama administration responded to the violence less than two months before the President's re-election.

Few issues reveal the hyper-partisan politics of Washington more than the ongoing debate over an issue now known simply as Benghazi.

On Friday, House Oversight Committee Chairman Darrell Issa announced that he has subpoenaed Secretary of State John Kerry to testify at a May 21 hearing on the issue.

A day earlier, House Speaker John Boehner accused the administration of defying a previous subpoena by failing to turn over newly disclosed documents, while Issa, a California Republican, said the transgression was "in violation of any reasonable transparency or historic precedent at least since Richard Milhous Nixon."

At the White House, spokesman Jay Carney shot back that Republicans continued trying to reap political benefit with what he called conspiracy theories about a Benghazi cover-up.

"What we have seen since hours after the attack, beginning with a statement by the Republican nominee for president, is an attempt by Republicans to politicize a tragedy, and that continues today," Carney told reporters, later adding that "what hasn't changed has been the effort by Republicans to ... claim a conspiracy when they haven't been able to find one."

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