WASHINGTON (CNN) -- Sen. John Kerry, D-Massachusetts, described his controversial remarks at a political rally Monday as a "botched joke" and sharply condemned GOP critics who have called for him to apologize.

"My statement yesterday, and the White House knows this full well, was a botched joke about the president, and the president's people, not about the troops," Kerry Tuesday said at a news conference in Seattle. "The White House's attempt to distort my true statement is a remarkable testament to their abject failure in making America safe."

Kerry came under fire Tuesday from Sen. John McCain, R-Arizona, White House spokesman Tony Snow and other Republican leaders for saying students who do not take their academics seriously will get "stuck" in Iraq.

"You know our education, if you make the most of it, you do your homework, and you make an effort to be smart, you can do well," Kerry said at the political rally for California gubernatorial candidate Phil Angelides. "If you don't, you get stuck in Iraq."