SUMMARY: The Democrats slugged it out in a Las Vegas debate. We found several claims were true, but Obama was wrong about the probability of lightning strikes vs. undocumented worker prosecutions.

Las Vegas, home to many a prizefight, was the perfect setting for the raucous debate between the Democratic candidates on Nov. 15, 2007.

Hillary Clinton, the target of many attacks, fired back by accusing her rivals of "throwing mud" and taking a page "right out of the Republican playbook."

We sorted out the truth on these claims:

* Sen. Barack Obama tried to make the point that enforcement against people who hire undocumented workers has to improve. We found his comparison to lightning strikes was False.

* Sen. Hillary Clinton took a shot at former Sen. John Edwards for flip-flopping on universal health care. We found her claim was True.

* Rep. Dennis Kucinich, usually closely allied with labor unions, said he's not "a slam dunk" on all labor issues and cited how he differed with the Teamsters union on drilling in Alaska's Arctic National Wildlife Refuge. We found his claim was True.

* New Mexico Gov. Bill Richardson correctly cited a report from the Government Accountability Office that said three out of 18 benchmarks for progress in Iraq have been fulfilled. We gave him a True.

* Richardson sought to distance himself from his rivals, who are either current or former members of Congress. He said, "Let me just say the Congress' approval rating is 11 percent. Now, you know who's higher? Dick Cheney and HMOs." We checked the poll numbers and found Richardson was way off. We gave him a False.