Some of our major presidential candidates have sounded recently like they think they're scientists.

When President Bush met with Mexico President Felipe Calderon and Canadian Prime Minister Steven Harper in New Orleans this week, the agenda focused largely on free trade issues and border security. "As continental neighbors and partners committed to democratic government, the rule of law and respect for individual rights and freedoms, Canada, Mexico and the United States have shared interests in keeping North America secure, prosperous, and competitive in today's global environment.

"Grand Theft Auto IV", the latest chapter of a highly controversial and breathtakingly successful video game franchise, arrives in stores on April 29.

In a long election campaign, candidates rarely miss a chance to seize on an opponent's off-the-cuff statements in hopes of taking advantage and winning support. Sometimes the criticism is dead-on accurate. Sometimes, a comment is ripped out of context and distorted unfairly.

One of the most common criticisms of illegal immigration is that immigrants pay little or no taxes, yet still receive government services paid for by tax-paying U.S. citizens. This criticism was repeated again recently by Missouri Treasurer Sarah Steelman as she opened her campaign for governor of that state:

Much has been made in recent days of an apparent gaffe by John McCain. He has suggested, on several occasions that Iran and Al Qaeda are cooperating in Iraq -- even though Iran is a Shiite Muslim country and Al Qaeda a Sunni Muslim organization. Fox News documents the initial fracas:

What strange bedfellows politicians make. Not a year goes by that some elected official, somewhere, isn’t caught up in some salacious scandal. Edwin Edwards, the crooked ex-governor of Louisiana, famously said in 1983, “The only way I can lose this election is if I'm caught in bed with either adead girl or a live boy.” The history of American politics is replete with both -- and then some.

Remember this?

"We know he's out trying once again to produce nuclear weapons and we know that he has a long-standing relationship with various terrorist groups, including the al-Qaeda organization," Vice President Dick Cheney said of Saddam Hussein on NBC's Meet The Press March 16, 2003.

The tightening of the Democratic race has brought, in recent days, allegations of subliminal dirty tricks in campaign advertising.

About 11 seconds into the Hillary Clinton spot above -- the infamous "3 a.m." advertisement challenging Barack Obama's qualifications -- a child is seen sleeping in alphabet pajamas. Ann Althouse publicized questions raised by a commenter:

With the campaigns for the Democratic nomination running so closely, the media and party activists have begun to focus on how some 796 "superdelegates" will cast their votes at the Democratic National Convention in August. The numbers are key. There are 4,049 total delegate votes total. A candidate needs 2,025 to secure the nomination. Of those delegates, superdelegates count for about one-fifth of the votes at the convention.