US Sen. John Kerry, D-Mass, speaks in support of California gubernatorial candidate Phil Angelides at a rally held at Pasadena City College in Pasadena, Calif., Monday, Oct. 30, 2006. [AP]

WASHINGTON - US Democratic Senator John Kerry said Wednesday he was sorry about a "botched joke" that drew election-year fire from President George W. Bush and other Republicans who accused him of insulting US troops in Iraq.

Kerry reiterated the target of his joke was Bush, who immediately seized on the senator's remarks to rally Republican supporters ahead of Tuesday's elections, in which the party's control of Congress is at risk.

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Kerry said he was returning to Washington from a trip campaigning on behalf of Democratic congressional candidates because he did not want to be "a distraction."

A day after rejecting calls to apologize for his remarks, Kerry, appearing on the "Imus in the Morning" radio show on MSNBC, declared: "I said it was a botched joke. Of course, I'm sorry about a botched joke."

While campaigning in California on Monday, Kerry told a college crowd: "You know, education, if you make the most of it, you study hard, you do your homework and you make an effort to be smart, you can do well. If you don't, you get stuck in Iraq."

Kerry's office said the senator had misread his prepared remarks. They said he had intended to say, "Do you know where you end up if you don't study, if you aren't smart, if you're intellectually lazy? You end up getting us stuck in a war in Iraq. Just ask President Bush."

The White House had pressed Kerry yesterday to apologize, saying he "put gasoline on the fire" of an already sizzling midterm election campaign.

"Senator Kerry may have botched the line, but what he said was insulting to the troops, and what he ought to say is, 'Look, I botched the line, but I'm sorry for giving offence," press secretary Tony Snow said on CBS's "The Early Show."

"We're not the one who whipped this up into a big issue. Senator Kerry did so yesterday," said Snow, appearing the day after President George W. Bush and Kerry traded their harshest accusations since the 2004 presidential race. Bush accused the Massachusetts Democrat of troop-bashing and Kerry called the president's men hacks who are "willing to lie" to gloss over problems with the war policy.

The fiery exchange evoked memories of 2004, injecting more adrenaline into what has been a taut midterm election fight between Republicans trying to cling to control of Congress and Democrats striving to win it back.

As Republicans demanded that Kerry apologize, a Democratic congressional candidate in a close race in Iowa cancelled a campaign event with Kerry, saying the senator's comments were inappropriate. And Kerry cancelled an appearance for a Democratic candidate in Minnesota.

Bush, campaigning in Georgia, said Kerry's statement was "insulting and it is shameful."

Kerry, who is considering another run for the White House in 2008, told a hastily called news conference, "I apologize to no one for my criticism of the president and of his broken policy."

But he also said the comment was "a botched joke about the president and the president's people, not about the troops ... and they know that's what I was talking about."